Necessity, oftener than facility, has been the mother of invention; and the most prolific school of all has been the school of difficulty. [ Samuel Smiles ]

Truth only is prolific. Error, sterile in itself, produces only by means of the portion of truth which it contains. It may have offspring, but the life which it gives, like that of the hybrid races, cannot be transmitted. [ Madame Swetchine ]

Local esteem is far more conducive to happiness than general reputation. The latter may be compared to the fixed stars which glimmer so remotely as to afford little light and no warmth. The former is like the sun, each day shedding his prolific and cheering beams. [ W. B. Clulow ]

A prolific source of obscurity is ambiguous arrangement. A member of the Savage Club, so runs the story, was one day standing on the steps of the club house. A messenger stopped and inquired: Does a gentleman belong to your club with one eye named Walker? I don't know, was the answer, what was the name of his other eye? [ Sir J. F. Stephen, The Art of Authorship, 1891 ]