Lenses and Waves

1690 - TRAITÉ DE LA LUMIÈRE 251
a conception, and noted that Mariotte had not been able to verify the
invariability of colored rays. He thought it was difficult to explain refraction
with light conceived as particles. He still preferred Huygens’ hypothesis but
also wanted his opinion on the matters discussed by Fatio. 134
In reply to Leibniz, Huygens wrote he was glad that his theory was being
approved of, although he was not pleased to see it equated with those of
Hooke and Pardies as the Wittenberg professor did. 135 For one thing, Pardies
and Hooke had not been able to explain the “…bizarreries du cristal
d’Islande, …” The explanation of strange refraction was the ‘Experimentum
Crucis’ of his theory and as long as they could not explain ordinary refraction
satisfactorily – let alone strange refraction – their views lacked a solid
foundation. As regards Newton’s nice and interesting observations on
different refrangibility, Huygens was of the same opinion as of universal
gravitation: “… he does not explain what color in those rays is, and it is
because of this that I, too, have not been fully satisfied until now.” 136 What
Huygens’ own thoughts on colors were, he once again did not tell.
Leibniz went so far as to place Traité de la Lumière at the same level as
Principia: these were in his view the two most important works in
contemporary science. 137 In this, Leibniz was the exception. Huygens
believed that he had surpassed all his predecessors in establishing a plausible
cause for the laws of optics. It was not hailed by his contemporaries as the
success he saw in it. Newton, for one, was not convinced by its argument as
he rejected a wave conception of light altogether. And he probably was not
impressed by Huygens’ arguments against an emission conception. But he
did take the trouble to discuss the difficulties of a wave conception in detail.
In addition, he gave his own account of strange refraction, apparently in
order to undo the uniqueness of Huygens’ explanation. After all, one
strength of Huygens’ wave theory was that it was the only one that could
explain this phenomenon. As Fatio put it:
“You, Monsieur, always have the advantage, that one cannot claim to have something
better until one has explained the phenomena of Iceland crystal so successfully …” 138
This was true for the few – Leibniz, Papin, de la Hire – who accepted
Huygens’ theory, but not for the majority in the eighteenth century who did
not. 139 Even ’s Gravesande, who published Opera Varia and Opera Reliqua of
Huygens, in optics followed Newton in his widespread textbook Physices
elementa mathematica of 1720.
134
OC10, 602. According to Fatio, Newton’s view that space is empty posed a serious but not
insurmountable problem for Huygens’ theory: OC10, 606.
135
OC10, 611-612.
136
OC10, 613. “… il n’explique pas ce que c’est que la couleur dans ces raions, et c’est en quoy je ne me
suis pas pleinement satisfait non plus jusqu’à present.”
137
Heinekamp, “Huygens vu par Leibniz”, 108.
138
OC9, 381; translation: Shapiro, “Kinematic optics”, 244.
139
Shapiro, “Kinematic optics”, 245. Shapiro offers a concise discussion of the way several scholars
understood and reacted upon the physical concepts of Huygens’ wave theory: 245-252.