 The second point to be noticed is that, according to Feigl’s version of the identity theory, the mode of ascertainment of the identity of the mental (raw feels) and the physical (neural processes) is empirical in character. Had Feigl in his first publication on the mind-body problem in 1934 assumed that the relationship between the mental and the physical is that of a logical identity (thereby implying that the language of psychology can be fully translated into the language of physics, viz. neurophysiology), he, in his later writings, no longer conceived of that identity as a logically necessary, but as an empirical (contingent) kind of identity. This meant, in the first place, that the corroboration of the philosophically outlined monism had to be provided, not by philosophical analysis again, but by the factual sciences themselves. “On the whole,” Feigl concluded: