His collecting propensities made him useful to John Ray and Robert Boyle.
As a commercial product spider-silk has been found to be equal, if not superior, to the best silk spun by lepidopterous larvae; but the cannibalistic propensities of spiders, making it impossible to keep more than one in a single receptacle, coupled with the difficulty of getting them to spin freely in a confined space, have hitherto prevented the silk being used on any extensive scale for textile fabrics.
So long as he lived he was a check upon the worst propensities of the king's administration.
But he does not seriously trouble himself to argue with egoism, or to weigh carefully the amount of happiness that might be generally attained by the satisfaction of egoistic propensities duly regulated; a supreme unquestioning self-devotion, in which all personal calculations are suppressed, is an essential feature of his moral ideal.
For this decision there were good reasons, for those turbulent sons of the steppe paid no taxes and were much given to brigandage, and their raiding propensities occasionally created international difficulties with the khan of the Crimea and the sultan of Turkey.
In the early part of the 19th century the island was chiefly known to Europeans on account of the wrecks which took place on its coasts, and the dangers that the crews had to run from the cannibal propensities of the aborigines, and the almost equally cruel tendencies of the Chinese.
The essence of his views is contained in the following passage, which he follows up with the conclusion "that one and the same kind of living filaments is and has been the cause of all organic life": "Would it be too bold to imagine that, in the great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, - would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the great First Cause endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions and associations, and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down these improvements by generation to its posterity, world without end!"
The Stanwick nectarine, so apt to crack and not to ripen when worked in the ordinary way, is said to be cured of these propensities by being first budded close to the ground, on a very strong-growing Magnum Bonum plum, worked on a Brussels stock, and by then budding the nectarine on the Magnum Bonum about a foot from the ground.
Herder defines human history as " a pure natural history of human powers, actions and propensities, modified by time and place."
The first stage is the eradication of vicious habits: evil tendencies are to be corrected, and a guard kept on the corrupt propensities of the reason.