Human and social facts, from their more complicated nature, are not less, but more, modifiable than mechanical and chemical facts
 John Stuart Mill, A System Of Logic, Ratiocinative And Inductive (1843). copy citation

Context

“However universal the laws of social development may be, they can not be more universal or more rigorous than those of the physical agencies of nature; yet human will can convert these into instruments of its designs, and the extent to which it does so makes the chief difference between savages and the most highly civilized people. Human and social facts, from their more complicated nature, are not less, but more, modifiable than mechanical and chemical facts; human agency, therefore, has still greater power over them. And accordingly, those who maintain that the evolution of society depends exclusively, or almost exclusively, on general causes, always include among these the collective knowledge and intellectual development of the race.” source