It is apt to be supposed that the copula is something more than a mere sign of predication; that it also signifies existence.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill
Therefore the circumstance of time is properly considered as attaching to the copula, which is the sign of predication, and not to the predicate.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill
In all these cases the subject of the predication is an entire proposition.
"A System Of Logic, Ratiocinative And Inductive (Vol. 1 of 2)"
John Stuart Mill