Perception is the first operation of our intellectual faculties and the necessary inlet and first de… — John Locke

Perception is the first operation of our intellectual faculties and the necessary inlet and first degree of all knowledge; the number and acuity of a creature’s senses and intellectual faculties determine how close or remote it is from the degree of knowledge found in some men.

By John Locke, from An Essay Concerning Human Understanding

Key Arguments

Locke explicitly identifies perception as epistemically primary: it is 'the first step and degree towards knowledge, and the inlet of all the materials of it'.
He links epistemic richness to sensory richness and sharpness: 'the fewer senses any man, as well as any other creature, hath; and the fewer and duller the impressions are that are made by them, and the duller the faculties are that are employed about them — the more remote are they from that knowledge which is to be found in some men.'
He notes that there is 'great variety of degrees (as may be perceived amongst men)' in perception and corresponding knowledge, though he says we cannot 'certainly be discovered in the several species of animals, much less in their particular individuals', which implies a graded continuum of cognitive capacity grounded in perception.
He summarizes the doctrinal point: 'It suffices me only to have remarked here — that perception is the first operation of all our intellectual faculties, and the inlet of all knowledge in our minds.'

Source Quotes

Perception the inlet of all materials of knowledge. Perception then being the first step and degree towards knowledge, and the inlet of all the materials of it; the fewer senses any man, as well as any other creature, hath; and the fewer and duller the impressions are that are made by them, and the duller the faculties are that are employed about them — the more remote are they from that knowledge which is to be found in some men. But this being in great variety of degrees (as may be perceived amongst men) cannot certainly be discovered in the several species of animals, much less in their particular individuals.

But this being in great variety of degrees (as may be perceived amongst men) cannot certainly be discovered in the several species of animals, much less in their particular individuals. It suffices me only to have remarked here — that perception is the first operation of all our intellectual faculties, and the inlet of all knowledge in our minds. And I am apt too to imagine, that it is perception, in the lowest degree of it, which puts the boundaries between animals and the inferior ranks of creatures.

Key Concepts

Perception then being the first step and degree towards knowledge, and the inlet of all the materials of it;
the fewer senses any man, as well as any other creature, hath; and the fewer and duller the impressions are that are made by them, and the duller the faculties are that are employed about them — the more remote are they from that knowledge which is to be found in some men.
It suffices me only to have remarked here — that perception is the first operation of all our intellectual faculties, and the inlet of all knowledge in our minds.

Context

Book II, chapter IX, section 15, where Locke concludes his discussion of perception by assigning it the foundational role in the acquisition and degree of human and animal knowledge.