Suppose that in a few years these theories are subjected to new tests and come out triumphant. Our secondary education will then run a great risk. Some teachers will no doubt wish to make room for the new theories. Novelties are so attractive, and it is so hard not to appear sufficiently advanced! The children will be warned that ordinary Mechanics has had its day, and that at most it was only good for such an old fogey as Laplace… Is it good to warn them that [the old mechanics] is only approximate? Certainly, but not till later on; when they are steeped to the marrow in the old laws and are no longer in danger of unlearning them. Then they may safely be shown their limitations. It is with the ordinary mechanics that they have to live; it is the only kind they will ever have to apply. Whatever be the progress of motoring, our cars will never attain the velocities at which its laws cease to be true. The other is only a luxury, and we must not think of luxury until there is no longer any risk of its being detrimental to what is necessary.

I shall leave this quandary, and I shall conclude with the following reflection. As science progresses, it becomes more and more difficult to make room for a new fact which does not fit in naturally. The older theories rest on a large number of numerical coincidences which cannot be attributed to chance. We cannot therefore put asunder that which they have joined together; we can no longer destroy the framework, we must try to “bend” it. And it does not always lend itself to this. The principle of equipartition of energy explained so many facts that it must contain some truth; on the other hand, it is not entirely true since it does not explain all the facts. We can neither discard it nor retain it without modification, and the modifications which seem imperative are so strange that we hesitate to accept them. In the present state of science, we can only admit these difficulties without resolving them.