John Locke

“ The mind can neither make nor destroy them. 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. When the understanding is once stored with these simple ideas, it has the power to repeat, compare, and unite them, even to an almost infinite variety, and so can make at pleasure new complex ideas. ”

“ But 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 : nor can any force of the understanding destroy those that are there. 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 ”

“ Only the qualities that affect the senses are imaginable. This is the reason why – though we cannot believe it impossible to God to make a creature with other organs, and more ways to convey into the understanding the notice of corporeal things than those five, as they are usually counted, which he has given to man – yet I think it is not possible for any man to imagine any other qualities in bodies, howsoever constituted, whereby they can be taken notice of, besides sounds, tastes, smells, visible and tangible qualities. ”

“ He that will not set himself proudly at the top of all things, but will consider the immensity of this fabric, and the great variety that is to be found in this little and inconsiderable part of it which he has to do with, may be apt to think that, in other mansions of it, there may be other and different intelligent beings, of whose faculties he has as little knowledge or apprehension as a worm shut up in one drawer of a cabinet hath of the senses or understanding of a man ”

“ The better to understand the nature, manner, and extent of our knowledge, one thing is carefully to be observed concerning the ideas we have ; and that is, that some of them are simple and some complex. ”

“ And had mankind been made but with four senses, the qualities then which are the objects of the fifth sense had been as far from our notice, imagination, and conception, as now any belonging to a sixth, seventh, or eighth sense can possibly be ”