We may first trace in outline the history of the birth of palaeontological ideas, from the time of their first adumbration.
The first adumbration was forced upon him in the former work by his theory of opposition; the complete appearance in the latter work by his theory of syllogism.
With this may be compared a passage in the Ursprung der Sprache, where there is a curious adumbration of Spencer's idea that intelligence, as distinguished from instinct, arises from a growing complexity of action, or, to use Herder's words, from the substitution of a more for a less contracted sphere.
Afterwards (chap. so) proceeding to the opposition of propositions, he adds the form called tertii adjacentis, in a passage which is the first appearance, or rather adumbration, of the verb of being as a copula.