Things in themselves


[1 of 7] Kant, Immanuel (1724-1804, Germany): primary subject "Philosophy, extracts" (search under Inner Life/Mind, Psyche, Soul, Spirit)": detail "‘Critique of Pure Reason: First Section of the Transcendental Aesthetic’ part 3, A (first version) 30"
The transcendental conception, on the contrary, of all phenomena in space, is a critical warning that nothing which is seen in space is a thing by itself, nor space a form of things supposed to belong to them by themselves, but that objects by themselves are not known to us at all, and that what we call external objects are nothing but representations of our senses, the form of which is space, and the true correlative of which, that is the thing by itself, is not known, nor can be known by these representations, nor do we care to know anything about it in our daily experience.

[2 of 7] Kant, Immanuel (1724-1804, Germany): primary subject "Philosophy, extracts" (search under Inner Life/Mind, Psyche, Soul, Spirit)": detail "‘Critique of Pure Reason: Of the Synthesis of Reproduction in Imagination’ II"
All phenomena are not things by themselves, but only the play of our representations, all of which are in the end determinations only of the internal sense.

[3 of 7] Kant, Immanuel (1724-1804, Germany): primary subject "Science, laws and observations" (search under Cosmology/Science)": detail "‘Critique of Judgment’, 1793, part I, section IX"
The intellect, by the possibility of its supplying a priori laws for nature, furnishes a proof of the fact that nature is understood by us only as a phenomenon, and in so doing points to nature’s having a supersensible substratum [‘thing-in-itself’]; but the intellect leaves this substratum quite undetermined.

[4 of 7] Kant, Immanuel (1724-1804, Germany): primary subject "Philosophy, extracts" (search under Inner Life/Mind, Psyche, Soul, Spirit)": source "Prolegomena to Any Future Metaphysics": detail "‘The Main Transcendental Question’ Third part, section 57 (Conclusion)"
Appearances always presuppose a thing in itself, and so provide notice of such a thing, whether or not it can be cognized more closely.

[5 of 7] Vivekananda (1863-1902, India): primary subject "Reality, observations on" (search under Inner Life/Teachings)": detail "From ‘Sankhya and Vedanta’"
Let us examine our perceptions. I see a blackboard. How does the knowledge come? What the German philosophers call "the thing-in-itself" of the blackboard is unknown, I can never know it. Let us call it x. The blackboard x acts on my mind, and the mind reacts. The mind is like a lake. Throw a stone in a lake and a reactionary wave comes towards the stone; this wave is not like the stone at all, it is a wave. The black-board x is like a stone which strikes the mind and the mind throws up a wave towards it, and this wave is what we call the blackboard. I see you. You as reality are unknown and unknowable. You are x and you act upon my mind, and the mind throws a wave in the direction from which the impact comes, and that wave is what I call Mr. or Mrs. So-and-so. There are two elements in the perception, one coming from outside and the other from inside, and the combination of these two, x + mind, is our external universe. All knowledge is by reaction. … Similar is the case with internal perception. The real self within me is also unknown and unknowable. Let us call it y. When I know myself as so-and-so, it is y + the mind. That y strikes a blow on the mind. So our whole world is x + mind (external), and y + mind (internal), x and y standing for the thing-in-itself behind the external and the internal worlds respectively. …
 The y, the internal thing-in-itself, combines with mind and manufactures existence, knowledge, and love. … When it gets mixed up, muddled up, as it were, with the mind, it becomes what we call individual existence. It is plant life, animal life, human life, just as universal space is cut off in a room, in a jar, and so on. And that real knowledge is not what we know, not intuition, nor reason, nor instinct. When that degenerates and is confused, we call it intuition; when it degenerates more, we call it reason; and when it degenerates still more, we call it instinct. …
 Now we will take up our x and y and show they are one. We have shown how what we call the external worlds is x + mind, and the internal world y + mind; x and y are both quantities unknown and unknowable. All difference is due to time, space, and causation. These are the constituent elements of the mind. No mentality is possible without them. You can never think without time, you can never imagine anything without space, and you can never have anything without causation. These are the forms of the mind. Take them away, and the mind itself does not exist. All difference is, therefore, due to the mind. According to Vedanta, it is the mind, its forms, that have limited x and y apparently and made them appear as external and internal worlds. But x and y, being both beyond the mind, are without difference and hence one. We cannot attribute any quality to them, because qualities are born of the mind. That which is qualityless must be one; x is without qualities, it only takes qualities of the mind; so does y; therefore these x and y are one. The whole universe is one.

[6 of 7] Kant, Immanuel (1724-1804, Germany): primary subject "Philosophy, extracts" (search under Inner Life/Mind, Psyche, Soul, Spirit)": detail "'Critique of Pure Reason' pp. 28,35, 36 (trans. J.M.D. Meiklejohn, 1878)"
Nothing which is intuited in space is a thing in itself, and space is not a form which belongs as a property to things; but objects are quite unknown to us in themselves, and what we call outward objects are nothing else but mere representations of our sensibility, whose form is space, but whose real correlate, the thing in itself, is not known by means of these representations, nor ever can be, but respecting which, in experience, no inquiry is ever made. …
 The things which we intuit are not in themselves the same as our representations of them in intuition, nor are their relations in themselves so constituted as they appear to us; and if we take away the subject, or even only the subjective constitution of our senses in general, then not only the nature and relations of objects in space and time, but even space and time themselves disappear. …
 What may be the nature of objects considered as things in themselves and without reference to the receptivity of our sensibility is quite unknown to us. We know nothing more than our mode of perceiving them. … Supposing that we should carry our empirical intuition [sensory perception] even to the very highest degree of clearness, we should not thereby advance one step nearer to the knowledge of the constitution of objects as things in themselves. …

[7 of 7] Ouspensky, Pyotr D. (1878-1947, Russia): primary subject "Reality, observations on" (search under Inner Life/Teachings)": source "New Model of the Universe": detail "Chapter 5"
Speculative philosophy arrives at the conclusion that the world undoubtedly exists, but that our conception of the word is false. This means that the causes of our sensations which lie outside ourselves really exist, but that our conception of these causes is false. Or, to put it another way, it means that the world in itself, ie. the world by itself, without our perception of it, exists, but we do not know it and can never reach it, because all that is accessible to our study, ie. the whole world of phenomena or manifestations, is only our percept of the world. We are surrounded by the wall of our own percepts and are unable to look over this wall into the real world.