Take even a simpler case, which seems more nearly resolvable into an expression of identity: 4=2+2. Even here, the meaning is not that the two members of the equation are identical, but only that the Concept or group four is equivalent in one respect – viz. the possession of an equal number of units – to the two groups two and two. It is plain that one group cannot be identical with two groups, or that two distinct acts of the mind, each conceiving or grasping together two units, cannot be literally the same thing as one mental act conceiving four.
– Bowen, F. 1864. A Treatise on Logic, The Laws of Pure Thought Cambridge, England: Cambridge University Press (1864) p. 360-1