# Section III: Of the Other Qualities of Our Idea of Space and Time explained — A Treatise of Human Nature > Chapter companion for A Treatise of Human Nature by David Hume. ## What happens Hume applies his principle that all ideas derive from impressions to the ideas of space and time. He argues that the idea of extension is a copy of the impressions of colored points or tangible atoms, and that abstract ideas are particular ideas considered in a certain light. Similarly, the idea of time is derived from the succession of perceptions, not from any distinct impression, and cannot be applied to unchangeable objects without a fiction. He also argues that indivisible points of space and moments of time must be filled with sensible qualities to be conceivable. ## Themes in this chapter ### Empiricism and the Primacy of Impressions Hume applies the principle that all ideas derive from impressions to the ideas of space and time, arguing that they are copies of sensory impressions. ### Skepticism About the External World Hume's analysis reduces space and time to mere collections of perceptions, challenging the notion of an independent external reality. ### Custom and General Rules The formation of abstract ideas of space and time relies on custom and the habitual association of similar impressions. ## Character check-ins ### David Hume Author and narrator, presenting his philosophical arguments. ## Key lines > No discovery could have been made more happily for deciding all controversies concerning ideas, than that above-mentioned, that impressions always take the precedency of them, and that every idea, with which the imagination is furnished, first makes its appearance in a correspondent impression. The principle that impressions precede all ideas is the most useful discovery for settling disputes about ideas. _Hume reiterates his foundational empiricist principle._ > The table before me is alone sufficient by its view to give me the idea of extension. This idea, then, is borrowed from, and represents some impression, which this moment appears to the senses. The idea of extension comes from sensory impressions, like seeing a table. _Hume uses a concrete example to illustrate the origin of the idea of space._ > All abstract ideas are really nothing but particular ones, considered in a certain light; but being annexed to general terms, they are able to represent a vast variety, and to comprehend objects, which, as they are alike in some particulars, are in others vastly wide of each other. Abstract ideas are just particular ideas used generally, representing many similar objects. _Hume explains his nominalist theory of abstract ideas._ > The idea of time, being derived from the succession of our perceptions of every kind, ideas as well as impressions, and impressions of reflection as well as of sensations will afford us an instance of an abstract idea, which comprehends a still greater variety than that of space, and yet is represented in the fancy by some particular individual idea of a determinate quantity and quality. Time is an abstract idea derived from the succession of all perceptions, even more varied than space. _Hume introduces the idea of time as derived from succession._ > A man in a sound sleep, or strongly occupied with one thought, is insensible of time; and according as his perceptions succeed each other with greater or less rapidity, the same duration appears longer or shorter to his imagination. When we are asleep or focused, we don't perceive time; its length depends on the rate of our perceptions. _Hume illustrates that time is only perceived through succession._ > If you wheel about a burning coal with rapidity, it will present to the senses an image of a circle of fire; nor will there seem to be any interval of time betwixt its revolutions; merely because it is impossible for our perceptions to succeed each other with the same rapidity, that motion may be communicated to external objects. A fast-moving coal appears as a continuous circle because our perceptions can't keep up with the motion. _Hume uses this example to show that time perception depends on the speed of our perceptions._ > Wherever we have no successive perceptions, we have no notion of time, even though there be a real succession in the objects. Without successive perceptions, we have no idea of time, even if objects change. _Hume emphasizes that time is subjective, based on perception._ > It is evident, that time or duration consists of different parts: For otherwise we could not conceive a longer or shorter duration. It is also evident, that these parts are not coexistent: For that quality of the coexistence of parts belongs to extension, and is what distinguishes it from duration. Time has parts that are not simultaneous, unlike space, which has coexisting parts. _Hume distinguishes time from space by the non-coexistence of its parts._ > The idea of time is not derived from a particular impression mixed up with others, and plainly distinguishable from them; but arises altogether from the manner, in which impressions appear to the mind, without making one of the number. Time is not a separate impression but arises from the way impressions succeed each other. _Hume argues that time is not a distinct impression but a manner of appearance._ > Five notes played on a flute give us the impression and idea of time; though time be not a sixth impression, which presents itself to the hearing or any other of the senses. Hearing five notes gives us the idea of time, but time is not an additional sound. _Hume uses the flute example to show that time is not a separate sense impression._ > But here it only takes notice of the manner, in which the different sounds make their appearance; and that it may afterwards consider without considering these particular sounds, but may conjoin it with any other objects. The mind notices the manner of succession and can abstract it from the specific sounds. _Hume explains how the idea of time can be abstracted from particular successions._ > I know there are some who pretend, that the idea of duration is applicable in a proper sense to objects, which are perfectly unchangeable; and this I take to be the common opinion of philosophers as well as of the vulgar. But to be convinced of its falsehood we need but reflect on the foregoing conclusion, that the idea of duration is always derived from a succession of changeable objects, and can never be conveyed to the mind by anything steadfast and unchangeable. Some think duration applies to unchanging objects, but that's false because duration comes from change. _Hume refutes the application of time to unchanging objects._ > The idea of space is conveyed to the mind by two senses, the sight and touch; nor does anything ever appear extended, that is not either visible or tangible. Space is perceived only through sight and touch; nothing extended is invisible or intangible. _Hume limits the idea of space to visual and tactile impressions._ > That compound impression, which represents extension, consists of several lesser impressions, that are indivisible to the eye or feeling, and may be called impressions of atoms or corpuscles endowed with colour and solidity. The impression of extension is made of tiny indivisible impressions, like colored and solid atoms. _Hume describes the minimal units of spatial perception._ > Upon the removal of the ideas of these sensible qualities, they are utterly annihilated to the thought or imagination. Without color or tangibility, points cannot be conceived. _Hume argues that spatial points must have sensible qualities to be imaginable._ ## Links - HTML: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters/section-iii-of-the-other-qualities-of-our-idea-of-space-and-time - Book: https://www.betterreads.online/discover/a_treatise_of_human_nature_se - All chapters: https://www.betterreads.online/discover/a_treatise_of_human_nature_se/chapters