Physics is experience, arranged in economical order.

The ego is as little absolutely permanent as are bodies.

Man is pre-eminently endowed with the power of voluntarily and consciously determining his own point of view.

Mathematics may be defined as the economy of counting. There is no problem in the whole of mathematics which cannot be solved by direct counting.

Scientists must use the simplest means of arriving at their results and exclude everything not perceived by the senses.

I once knew an otherwise excellent teacher who compelled his students to perform all their demonstrations with incorrect figures, on the theory that it was the logical connection of the concepts, not the figure, that was essential.

The presentations and conceptions of the average man of the world are formed and dominated, not by the full and pure desire for knowledge as an end in itself, but by the struggle to adapt himself favourably to the conditions of life.