He shows elaborately how the pleasures and pains of " imagination, ambition, self-interest, sympathy, theopathy, and the moral sense " are developed out of the elementary pleasures and pains of sensation; by the coalescence into really complex but apparently single ideas of the " miniatures " or faint feelings which the repetition of sensations contemporaneously or in immediate succession tends to produce in cohering groups.
Such sheet or wire then remains flexible after cooling, the originally only loosely cohering crystals having got intertwisted and forced into absolute contact with one another - an explanation supported by the fact that rolled zinc has a somewhat higher specific gravity (7.2) than the original ingot (6.9).
The leaves are borne in whorls, those of each whorl cohering, except at their extreme tips, to form a sheath.