I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.

I need scarcely say that the beginning and maintenance of life on earth is absolutely and infinitely beyond the range of all sound speculation in dynamical science. The only contribution of dynamics to theoretical biology is absolute negation of automatic commencement or automatic maintenance of life.

All of science can be divided into physics and stamp-collecting.

Science is bound, by the everlasting vow of honour, to face fearlessly every problem which can be fairly presented to it.

In science there is only physics; all the rest is stamp collecting.

Christianity without the cross is nothing. The cross was the fitting close of a life of rejection, scorn and defeat. But in no true sense have these things ceased or changed. Jesus is still He whom man despiseth, and the rejected of men. The world has never admired Jesus, for moral courage is yet needed in every one of its high places by him who would "confess" Christ. The "offense" of the cross, therefore, has led men in all ages to endeavor to be rid of it, and to deny that it is the power of God in the world.

There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.