Lenses and Waves

1690 - TRAITÉ DE LA LUMIÈRE 247
of the ether. Thus he mathematized the mechanistic foundations of natural
science, which Newton had not dared to. As regards the essential probability
of mechanistic explanations, Newton had drawn a conclusion opposite to
Huygens’. If speculations lead you astray, then stop speculating (at least in
public), Newton said. If they do so, speculate better, Huygens would say.
Huygens’ self-image
We have seen, in his comments on Baillet, how Huygens saw the merits and
faults of Descartes’ science. According to Huygens, Descartes had shown
what the principles of natural philosophy ought to be like, but at the same
time he had failed to elaborate them properly in explaining particular
phenomena. Still, if he had been too confident of the truth of his ideas, this
may have been a stimulus for so many to do better. The picture returns in
Discours:
“I confess that his essays, and his views, although false, have served to open to me the
road to what I have found on this very subject.” 116
Yet the clear and distinct ideas that had made such an impression on the
youthful Huygens were activated only occasionally during his scholarly
career. His science consisted primarily of mathematical inquiry, sometimes
inspired by his mechanistic thinking. He turned mechanistic philosopher
only rarely. He did so, in my view, mainly when he saw ghosts of the occult
thinking he thought Descartes had disposed of. 117 And he did so in Traité de la
Lumière, establishing the ‘raisons de mechanique’ of the laws of optics. Or
should we say that, with his waves, he went beyond mechanistic philosophy
by applying Galileo’s science of motion to the imperceptible particles of the
ether?
In his comments on Baillet’s biography, Huygens moved from a
reflection upon Descartes’ merits to a discussion of the virtues of other
natural inquirers. This is illuminating regarding the way he saw himself. The
ancient atomists had had the right categories, but could not explain natural
phenomena. Moderns like Telesio, Campanella and Gilbert were no better
than Aristotelians in that they maintained occult qualities. Gassendi and
Bacon exposed the inadequacies of Peripatetic philosophy but, like so many
moderns, lacked understanding in mathematics. Only one man could stand
the test of Huygens’ critique:
“For wit and knowledge of Mathematics Galileo had all that is necessary to make
progress in physics, and one must acknowledge that he has been the first to make
beautiful discoveries concerning the nature of motion although he has left very
considerable ones still to be made. He had neither the audacity nor the conceit to want
to take it upon himself to explain all natural causes, nor the vanity to wish to be head of
a sect. He was modest and loved the truth too much; he believed moreover to have
116 OC21, 446 (Discours, 127). “Et cependant j’avoue que ses essais, & ses vuës, quoyque fausses, ont servi
à m’ouvrir le chemin à ce que j’ay trouvé sur ce mesme sujet.”
117 Probably, in the eyes of new age thinkers like Lewis Mumford, this would turn Huygens into a criminal
of the stature of Galileo and Descartes. See Vanheste, Copernicus is ziek, 40-45.