What are simple and complex ideas?

John Locke, answered from the texts and cited to the page.

John Locke answers

The mind, as I have described it in the Essay Concerning Human Understanding, is at the outset like a dark room — a closet wholly shut from light, with only some little openings left to let in external visible resemblances, or ideas of things without.1 What enters through those openings are simple ideas, and they are the foundation of everything the understanding can ever possess.

Simple ideas enter the mind by two routes only: sensation, which furnishes ideas of external qualities, and reflection, which furnishes ideas of the mind's own operations upon those materials.2 They arrive unmixed. Though the qualities that affect our senses are in things themselves blended together — a man sees motion and colour at once, the hand feels softness and warmth in the same piece of wax — yet the ideas they produce in the mind enter simple and distinct, each containing nothing but one uniform appearance, not distinguishable into different ideas.3

Coldness and hardness in a piece of ice are as perfectly distinct in the mind as the smell and whiteness of a lily. Here is the constraint that governs everything: it is not in the power of the most exalted wit, or enlarged understanding, by any quickness or variety of thought, to invent or frame one new simple idea not taken in by those two ways.4

The dominion of man over his own understanding is much the same as his dominion over the great world of visible things — he can compound and divide the materials made to his hand, but he can do nothing toward making the least particle of new matter.5 I would have any one try to fancy a taste which had never affected his palate, or frame the idea of a scent he had never smelt; and when he can do this, I will conclude that a blind man has ideas of colours. Complex ideas are what the mind makes from these simple materials, once stored with them.6

The mind is wholly passive in the reception of simple ideas, but it exerts several acts of its own upon them.7 Those acts are chiefly three: first, combining several simple ideas into one compound one — and thus all complex ideas are made; second, setting two ideas by one another so as to take a view of them at once without uniting them, by which way the mind gets all its ideas of relations; third, separating an idea from all others that accompany it in real existence, which is called abstraction, and thus all general ideas are made.8

Beauty, gratitude, a man, an army, the universe — though complicated of various simple ideas — are each, when the mind pleases, considered as one entire thing and signified by one name.9 In this faculty of repeating and joining its ideas, the mind has great power in varying and multiplying the objects of its thoughts infinitely beyond what sensation or reflection furnished it with — but all this still confined to those simple ideas which it received from those two sources, which are the ultimate materials of all its compositions.10

The mind can put together ideas it has and make new complex ones which it never received so united; but it cannot go beyond the simple originals. This shews man's power and its way of operation to be much the same in the material and the intellectual world alike.11

Sources

  1. the Understanding is not much unlike a Closet wholly shut from light, with only some little openings left, to let in external visible Resemblances, or Ideas of things without
    An Essay Concerning Human Understanding, pp. 186–187
  2. These simple Ideas, the Materials of all our Knowledge, are suggested and furnished to the Mind, only by those two ways above mentioned, viz. Sensation and Reflection.
    An Essay Concerning Human Understanding, pp. 142–143
  3. Though the Qualities that affect our Senses, are, in the things themselves, so united and blended, that there is no separation, no distance between them; yet 'tis plain, the Ideas they produce in the Mind, enter by the Senses simple and unmixed.
    An Essay Concerning Human Understanding, pp. 142–143
  4. it is not in the Power of the most exalted Wit, or enlarged Understanding, by any quickness or variety of Thought, to invent or frame one new simple Idea in the mind, not taken in by the ways before mentioned
    An Essay Concerning Human Understanding, pp. 143–144
  5. The Dominion of Man, in this little World of his own Understanding, being muchwhat the same, as it is in the great World of visible things; wherein his Power, however managed by Art and Skill, reaches no farther, than to compound and divide the Materials, that are made to his Hand
    An Essay Concerning Human Understanding, pp. 143–144
  6. I would have any one try to fancy any Taste, which had never affected his Palate; or frame the Idea of a Scent, he had never smelt: And when he can do this, I will also conclude, that a blind Man hath Ideas of Colours
    An Essay Concerning Human Understanding, pp. 143–144
  7. the Mind is wholly Passive in the reception of all its simple Ideas, so it exerts several acts of its own, whereby out of its simple Ideas, as the Materials and Foundations of the rest, the other are framed
    An Essay Concerning Human Understanding, pp. 186–187
  8. The Acts of the Mind wherein it exerts its Power over its simple Ideas are chiefly these three, 1. Combining several simple Ideas into one compound one... 2. The 2d. is bringing two Ideas... together... 3. The 3d. is separating them from all other Ideas that accompany them in their real existence; this is called Adstraction
    An Essay Concerning Human Understanding, pp. 186–187
  9. Ideas thus made up of several simple ones put together, I call Complex; such as are Beauty, Gratitude, a Man, an Army, the Universe; which though complicated of various simple Ideas, or complex Ideas made up of simple ones, yet are, when the Mind pleases, considered each by it self, as one entire thing
    An Essay Concerning Human Understanding, pp. 187–188
  10. In this faculty of repeating and joining together its Ideas, the Mind has great power in varying and multiplying the Objects of its Thoughts, infinitely beyond what Sensation or Reflection furnished it with: But all this still confined to those simple Ideas, which it received from those two Sources, and which are the ultimate Materials of all its Compositions.
    An Essay Concerning Human Understanding, pp. 187–188
  11. This shews Man's Power and its way of Operation to be muchwhat the same in the Material and Intellectual World.
    An Essay Concerning Human Understanding, pp. 186–187