ll natural bodies have no other
origin than this, that they are variously qualified to reflect one sort
of light in greater plenty than another. And this I have experimented
in a dark room by illuminating those bodies with uncompounded light of
divers colors. For by that means any body may be made to appear of any
color. They have there no appropriate color, but ever appear of the
color of the light cast upon them, but yet with this difference, that
they are most brisk and vivid in the light of their own daylight color.
Minium appeareth there of any color indifferently with which 'tis
illustrated, but yet most luminous in red; and so Bise appeareth
indifferently of any color with which 'tis illustrated, but yet most
luminous in blue. And therefore Minium reflecteth rays of any color, but
most copiously those indued with red; and consequently, when
illustrated with daylight--that is, with all sorts of rays promiscuously
blended--those qualified with red shall abound most in the reflected
light, and by their prevalence cause it to appear of that color. And for
the same reason, Bise, reflecting blue most copiously, shall appear
blue by the excess of those rays in its reflected light; and the like
of other bodies. And that this is the entire and adequate cause of their
colors is manifest, because they have no power to change or alter
the colors of any sort of rays incident apart, but put on all colors
indifferently with which they are enlightened."(2)

This epoch-making paper aroused a storm of opposition. Some of Newton's
opponents criticised his methods, others even doubted the truth of his
experiments. There was one slight mistake in Newton's belief that all
prisms would give a spectrum of exactly the same length, and it was
some time before he corrected this error. Meanwhile he patiently met
and answered the arguments of his opponents until he began to feel that
patience was no longer a virtue. At one time he even went so far as to
declare that, once he was "free of this business," he would renounce
scientific research forever, at least in a public way. Fortunately for
the world, however, he did not adhere to this determination, but went
on to even greater discoveries--which, it may be added, involved still
greater controversies.

In commenting on Newton's discovery of the composition of light,
Voltaire said: "Sir Isaac Newton has demonstrated to the eye, by the
bare assistance of a prism, that light is a composition o