Men, women, and children will stand for hours watching the antics of goats enclosed in a pasture.
The goats will nibble the grass contentedly and soberly, until suddenly, as if pricked with a thorn, one or another will bound away for a short distance, perhaps prance a bit, or playfully butt another, and then with the utmost composure fall to nibbling grass again.
The young kids indulge more frequently in these sudden outbursts of exuberance and are, therefore, more amusing to watch, but the antics of the older ones are more unexpected. Now the Latin word for goat is capra.
Thus, from the unaccountable leaps upward, forward, or sideward of these animals has come our word caper.
And when, through a quirk of the mind, one indulges in something unexpected, we call such an action a caprice, and one is capricious when, through whim, he turns from one thing to another. (See also CAB.)