His approaching departure did not prevent his amusing himself, but rather gave zest to his pleasures.
Napoleon applied himself with more zest to his studies, in the hope of speedily qualifying himself for the artillery.
While maintaining intact its religious attitude and its theory of knowledge, it returned with new zest to scientific studies, especially the study of the old philosophers.
This high physical zest in life seems to have declined after 1831, when his eyes began to trouble him, and he became liable to depression.
The great philosophical impulse was that given by Darwin in 1859 through his demonstration of the theory of descent, which gave tremendous zest to the search for pedigrees (phylogeny) of the existing and extinct types of animal and plant life.