In relation to human society, and the rules it imposes on its members, action that ought not to be done is crime; a habit which is injurious to a man's own moral nature, especially if it involves evil physical consequences, is described as vice.
According to that theory, every organ, every part, colour and peculiarity of an organism, must either be of benefit to that organism itself or have been so to its ancestors: no peculiarity of structure or general conformation, no habit or instinct in any organism, can be supposed to exist for the benefit or amusement of another organism, not even for the delectation of man himself.
The habit of absolute rule, always dangerous, was peculiarly corrupting when it penetrated every department of daily life, and when no external interference checked individual caprice in its action on the feelings and fortunes of inferiors.
This habit can be used as a means of killing them, by placing boards or sacks covered with tar below the trees, which are then gently shaken.
Here and there a couple of bees, by force of habit and custom cleaning out the brood cells, with efforts beyond their strength laboriously drag away a dead bee or bumblebee without knowing why they do it.
His style has frequently been blamed for its obscurity and difficulty, but this is due to two causes: his habit of compressing his arguments into narrow compass, and of always writing with the opposite side of the case in view, so that it has been said of the Analogy that it raises more doubts than it solves.
Possibly from this habit was developed the instinct to build a door with a movable hinge.
This is undoubtedly due to constitutional weakness arising from bad nutrition and the habit of sleeping in closed or badly ventilated apartments.
In the middle ages it was a common practice for sovereigns and princes to dub each other knights much as they were afterwards, and are now, in the habit of exchanging the stars and ribbons of their orders.
Hume, therefore, for his part, rejected entirely the notion of cause as being fictitious and delusive, and professed to account for the habit of regarding experience as necessarily connected by reference to arbitrarily formed custom of thinking.