It is strange that only extraordinary men make the discoveries, which later appear so easy and simple.
The American who first discovered Columbus made a bad discovery.
If we make a couple of discoveries here and there we need not believe things will go on like this for ever. Just as we hit water when we dig in the earth, so we discover the incomprehensible sooner or later.
A good means to discovery is to take away certain parts of a system to find out how the rest behaves.
What we have to discover for ourselves leaves behind in our mind a pathway that can be used on another occasion.
People who have read a good deal rarely make great discoveries. I do not say this in excuse of laziness, but because invention presupposes an extensive independent contemplation of things.
A good method of discovery is to imagine certain members of a system removed and then see how what is left would behave: for example, where would we be if iron were absent from the world: this is an old example.
Astronomy is perhaps the science whose discoveries owe least to chance, in which human understanding appears in its whole magnitude, and through which man can best learn how small he is.