The supreme task of the physicist is to arrive at those universal elementary laws from which the cosmos can be built up by pure deduction. There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them.
...the physicist cannot simply surrender to the philosopher the critical contemplation of the theoretical foundations; for, he himself knows best, and feels more surely where the shoe pinches...Physical conceptions are free creations of the human mind, and are not, however it may seem, uniquely determined by the external world.
Ere land and sea and the all-covering sky Were made, in the whole world the countenance Of nature was the same, all one, well named Chaos, a raw and undivided mass, Naught but a lifeless bulk, with warring seeds Of ill-joined elements compressed together.
Chlorine is a deadly poison gas employed on European battlefields in World War I. Sodium is a corrosive metal which burns upon contact with water. Together they make a placid and unpoisonous material, table salt. Why each of these substances has the properties it does is a subject called chemistry.
But poverty, though it does not prevent the generation, is extremely unfavourable to the rearing of children. The tender plant is produced, but in so cold a soil, and so severe a climate, soon withers and dies.
The discovery of truth is prevented more effectively, not by the false appearance things present and which mislead into error, not directly by weakness of the reasoning powers, but by preconceived opinion, by prejudice.