microscopic studies that he boldly undertook to determine the
relationship of human thought to objective reality. He published his
views in the introduction to his Micrographia, the great work in which,
with the lavish help of carefully executed copper engravings, he made
his microscopic observations known to the world.

Hooke's line of thought is briefly as follows: In past ages men
subscribed to the naive belief that what they have in their
consciousness as thought pictures of the world, actually reproduces the
real content of that world. The microscope now demonstrates, however,
how much the familiar appearance of the world depends on the structure
of our sense apparatus; for it reveals a realm just as real as that
already known to us, but hitherto concealed from us because it is not
accessible to the natural senses. Accordingly, if the microscope can
penetrate through the veil of illusion which normally hides a whole
world of potentially visible phenomena, it may be that it can even
teach us something about the ideas we have hitherto formed concerning
the nature of things. Perhaps it can bring us a step nearer the truth
in the sphere of thought, as it so obviously has done in that of
observation.

Of all the ideas that human reason can form, Hooke considered the
simplest and the most fundamental to be the geometrical concepts of
point and straight line. Undoubtedly we are able to think these, but
the naïve consciousness takes for granted that it also perceives them as
objective realities outside itself, so that thoughts and facts
correspond to each other. We must now ask, however, if this belief is
not due to an optical deception. Let us turn to the microscope and see
what point and line in the external world look like through it.