1. My design is to shew the manner wherein we perceive by sight the distance, magnitude, and situation of objects. Also to consider the difference there is betwixt the ideas of sight and touch, and whether there be any idea common to both senses.
2. It is, I think, agreed by all that distance, of itself and immediately, cannot be seen. For distance being a Line directed end-wise to the eye, it projects only one point in the fund of the eye, which point remains invariably the same, whether the distance be longer or shorter.
3. I find it also acknowledged that the estimate we make of the distance of objects considerably remote is rather an act of judgment grounded on experience than of sense. For example, when I perceive a great number of intermediate objects, such as houses, fields, rivers, and the like, which I have experienced to take up a considerable space, I thence form a judgment or conclusion that the object I see beyond them is at a great distance. Again, when an object appears faint and small, which at a near distance I have experienced to make a vigorous and large appearance, I instantly conclude it to be far off: And this, 'tis evident, is the result of experience; without which, from the faintness and littleness I should not have inferred anything concerning the distance of objects.

George Berkeley, An Essay Towards a New Theory of Vision

General Philosophy Resources

Stanford Encyclopedia of Philosophy

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Peter Suber's Guide to Philosophy on the Internet

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History Resources

Classics in the History of Psychology

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The MacTutor History of Mathematics of Archive

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