Human beings do not all feel and act alike in the same circumstances
 John Stuart Mill, A System Of Logic, Ratiocinative And Inductive (1843). copy citation

Context

“yet all modes of feeling and conduct met with among mankind have causes which produce them; and in the propositions which assign those causes will be found the explanation of the empirical laws, and the limiting principle of our reliance on them. Human beings do not all feel and act alike in the same circumstances; but it is possible to determine what makes one person, in a given position, feel or act in one way, another in another; how any given mode of feeling and conduct, compatible with the general laws (physical and mental)” source