Philosophers on Spirit & Metaphysics

On the immortality of the soul:

"The soul is in the very likeness of the divine, and immortal, and intellectual, and uniform, and indissoluble, and unchangeable; and the body is in the very likeness of the human, and mortal, and unintellectual, and multiform, and dissoluble, and changeable."

Plato's metaphysics centered on his Theory of Forms, which held that the physical world is merely a shadow or imperfect copy of eternal Forms or Ideas. True reality consists of these perfect, immaterial Forms, and the soul exists before birth and after death, capable of knowing the Forms.

On first philosophy:

"All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight... The reason is that this, most of all the senses, makes us know and brings to light many differences between things."

On the unmoved mover:

"There is, then, something which is always moved with an unceasing motion, which is motion in a circle; and this is plain not in theory only but in fact. Therefore the first heaven must be eternal. There is therefore also something which moves it. And since that which moves and is moved is intermediate, there is something which moves without being moved, being eternal, substance, and actuality."

Aristotle developed a metaphysics that was more grounded in the physical world than Plato's. Forms exist within things, not in a separate realm; reality consists of substances with both form and matter; and he explored fundamental concepts like substance, causation, and the "unmoved mover"—a divine first cause of all motion.

On the One:

"The One is all things and no one of them; the source of all things is not all things; and yet it is all things in a transcendental sense—all things, so to speak, having run back to it, or, more correctly, not yet being in existence, but destined to be."

On emanation:

"The One overflows, as it were, and its superabundance makes something other than itself. This, when it has come into being, turns back upon the One and is filled, and becomes Intellect by looking toward it. Its halt and turning toward the One constitutes being, its gaze upon the One, Intellect."

Plotinus and other Neoplatonists developed Plato's ideas in a more mystical direction. Reality emanates from the One, a transcendent, ineffable source; the soul can ascend through contemplation to mystical union with the One; and evil is not a positive force but a privation or absence of good.

On the universal nature:

"Constantly regard the universe as one living being, having one substance and one soul; and observe how all things have reference to one perception, the perception of this one living being; and how all things act with one movement; and how all things are the cooperating causes of all things which exist; observe too the continuous spinning of the thread and the contexture of the web."

On the divine within:

"Live with the gods. And he does live with the gods who constantly shows to them that his own soul is satisfied with that which is assigned to him, and that it does all that the daemon wishes, which Zeus hath given to every man for his guardian and guide, a portion of himself. And this is every man's understanding and reason."

As a Stoic philosopher, Marcus Aurelius viewed the cosmos as a rational, ordered whole governed by divine reason (logos). He believed that human beings participate in this divine reason and should live in accordance with nature by cultivating virtue and accepting fate.

On Brahman and Atman:

"In the beginning, my dear, this world was just Being, one only, without a second. Some people, no doubt, say: 'In the beginning this world was just Non-being, one only, without a second; from that Non-being Being was produced.' But how, indeed, my dear, could it be so? How could Being be produced from Non-being? On the contrary, my dear, in the beginning this world was just Being, one only, without a second."

On the identity of self and ultimate reality:

"That which is the finest essence—this whole world has that as its soul. That is Reality. That is Atman. Tat tvam asi [That thou art]."

The Upanishads, foundational texts of Hindu philosophy, explored Brahman (the ultimate, unchanging reality underlying all existence), Atman (the true self or soul, identical with Brahman), and Maya (the illusory nature of the phenomenal world).

On impermanence:

"All conditioned things are impermanent—when one sees this with wisdom, one turns away from suffering. This is the path to purification."

On no-self:

"All conditioned things are not-self—when one sees this with wisdom, one turns away from suffering. This is the path to purification."

Early Buddhist philosophy developed distinctive metaphysical views: Anatta (no-self) denies a permanent, unchanging self or soul; Anicca (impermanence) holds that all phenomena are in constant flux; and Pratityasamutpada (dependent origination) teaches that all things arise in dependence on causes and conditions.

On the ineffable Dao:

"The Dao that can be told is not the eternal Dao. The name that can be named is not the eternal name. The nameless is the beginning of heaven and earth. The named is the mother of ten thousand things."

On complementary opposites:

"Under heaven all can see beauty as beauty only because there is ugliness. All can know good as good only because there is evil. Therefore having and not having arise together. Difficult and easy complement each other. Long and short contrast each other. High and low rest upon each other."

Classical Daoism presented the Dao as the ineffable source and pattern of all existence, emphasized wu-wei (non-action or action in harmony with nature), and viewed complementary opposites (yin-yang) as fundamental to reality.

On God and time:

"What, then, is time? If no one asks me, I know; if I want to explain it to someone who does ask me, I don't know."

On evil as privation:

"And I inquired what iniquity was, and found it to be no substance, but the perversion of the will, turned aside from Thee, O God, the Supreme, towards these lower things."

Augustine synthesized Neoplatonism with Christian theology, viewing God as the eternal, unchanging source of all being. He saw evil as privation or absence of good, not a substance, and the soul as immaterial and immortal, created by God.

On the existence of God:

"The existence of God can be proved in five ways. The first and more manifest way is the argument from motion... The second way is from the nature of the efficient cause... The third way is taken from possibility and necessity... The fourth way is taken from the gradation to be found in things... The fifth way is taken from the governance of the world."

On essence and existence:

"In God alone essence and existence are the same. In everything else, that which exists participates in existence."

Aquinas integrated Aristotelian philosophy with Christian doctrine, developing the Five Ways to prove God's existence (including the Unmoved Mover and First Cause arguments), distinguishing between essence and existence, and proposing the analogy of being: creatures participate in God's being analogically.

On the cogito:

"I think, therefore I am."

On God as guarantor of clear and distinct ideas:

"I have in my mind the idea of God as an infinite being, and since I am finite, this idea could not have originated with me but must have been placed in me by God himself."

Descartes' metaphysics established mind-body dualism: mind (res cogitans) and matter (res extensa) as distinct substances. The cogito ("I think, therefore I am") served as an indubitable foundation, and God as guarantor of clear and distinct ideas. His work raised the "mind-body problem" that would preoccupy later philosophers.

On substance monism:

"By substance I mean that which is in itself, and is conceived through itself: in other words, that of which a conception can be formed independently of any other conception."

On God or Nature:

"Whatever is, is in God, and nothing can exist or be conceived without God."

Spinoza developed a radical monism: only one substance exists (Deus sive Natura, "God or Nature"); mind and matter are attributes of this single substance; and all things follow with necessity from divine nature. This deterministic system identified God with nature and rejected free will.

On monads:

"The Monad, of which we shall here speak, is nothing but a simple substance, which enters into compounds. By 'simple' is meant 'without parts.'"

On pre-established harmony:

"Now this connection or adaptation of all created things to each other, and each to all the others, brings it about that each simple substance has relations that express all the others, and consequently, that each simple substance is a perpetual, living mirror of the universe."

Leibniz proposed a pluralistic metaphysics: monads (simple, immaterial substances) as fundamental units of reality; pre-established harmony (monads don't interact but are synchronized by God); and the principle of sufficient reason (everything has an explanation). He also developed theodicy, arguing that this is "the best of all possible worlds."

On the limits of knowledge:

"I have therefore found it necessary to deny knowledge, in order to make room for faith."

On phenomena and noumena:

"Thoughts without content are empty, intuitions without concepts are blind."

Kant's "Copernican Revolution" in metaphysics established the distinction between phenomena (things as they appear) and noumena (things in themselves). He argued that space and time are forms of intuition, not features of reality itself, and that categories of understanding structure our experience.

On dialectical development:

"The bud disappears when the blossom breaks through, and we might say that the former is refuted by the latter; in the same way when the fruit comes, the blossom may be explained to be a false form of the plant's existence, for the fruit appears as its true nature in place of the blossom. These stages are not merely differentiated; they supplant one another as being incompatible with one another."

On Absolute Spirit:

"The True is the whole. But the whole is nothing other than the essence consummating itself through its development."

Hegel developed an ambitious idealist metaphysics: Absolute Idealism views reality as the unfolding of Absolute Spirit or Mind; the dialectical method (thesis-antithesis-synthesis) describes the pattern of development; and history is seen as the rational process of Spirit's self-realization.

On the world as representation:

"The world is my representation."

On the world as will:

"The will, which, considered purely in itself, is without knowledge, and is merely a blind, irresistible urge, as we see it appear in inorganic and vegetable nature and in their laws, and also in the vegetative part of our own life, receives through the addition of the world as representation, which is developed in subjection to it, the knowledge of its own willing and of what it is that it wills."

Schopenhauer's metaphysics proposed the world as representation (appearance) and will (reality). Will is a blind, purposeless striving underlying all phenomena. Aesthetic contemplation and compassion offer temporary escapes from will. His pessimistic philosophy influenced Nietzsche, Freud, and existentialism.

On the question of Being:

"The question of the meaning of Being must be formulated... We are ourselves the entities to be analyzed. The Being of any such entity is in each case mine."

On Dasein:

"Dasein is an entity which does not just occur among other entities. Rather it is ontically distinguished by the fact that, in its very Being, that Being is an issue for it."

Heidegger's fundamental ontology analyzed Being and human existence (Dasein). Being and Time sought to reopen the question of Being after what he saw as its forgetting in Western metaphysics. His work influenced existentialism, hermeneutics, and postmodernism.

On process philosophy:

"That 'all things flow' is the first vague generalization which the unsystematized, barely analyzed, intuition of men has produced."

On actual occasions:

"The actual world is built up of actual occasions; and by the ontological principle whatever things there are in any sense of 'existence,' are derived by abstraction from actual occasions."

Whitehead's Process and Reality developed a metaphysics where reality is process rather than static substance, actual occasions (events) are the basic units of reality, and God is both primordial (eternal) and consequent (responsive to world). Process theology applied these ideas to religious thought.

On the hard problem of consciousness:

"The really hard problem of consciousness is the problem of experience. When we think and perceive, there is a whir of information-processing, but there is also a subjective aspect."

On property dualism:

"Consciousness is a feature of the world over and above the physical features of the world. This is not to say it is a separate 'substance'; the issue of what it would take for consciousness to be a separate substance seems quite unclear to me. All we know is that there are properties of individuals in this world—the phenomenal properties—that are ontologically independent of physical properties."

Chalmers formulated the "hard problem of consciousness": why physical processes give rise to subjective experience. He defends property dualism, arguing that consciousness is a fundamental, non-physical property that cannot be reduced to or explained by physical processes alone.

On pure experience:

"To experience means to know facts just as they are, to know in accordance with facts by completely relinquishing one's own fabrications. What we usually refer to as experience is adulterated with some sort of thought, so by pure I am referring to the state of experience just as it is without the least addition of deliberative discrimination."

On absolute nothingness:

"True emptiness is not the emptiness of nothingness, but the emptiness of fullness in which this and that, I and you, are identities in their differences."

Nishida, founder of the Kyoto School, synthesized Zen Buddhism with Western philosophy. His concept of "absolute nothingness" (zettai mu) is not mere negation but a dynamic field that encompasses and enables all being. His work offers an alternative to Western metaphysical frameworks.