John Stuart Mill,
A System of Logic, Ratiocinative and Inductive
“ Being is, by custom, exactly synonymous with substance; except that it is free from a slight taint of a second ambiguity; being implied impartially to matter and to mind, while substance, though originally and in strictness applicable to both, is apt to suggest in preference the idea of matter. Attributes are never called Beings; nor are feelings. ”
