If we examine the state of many animals which have no appetites leading them to excess, we may form a very just idea of a _physical-necessary_ for man. When they are free from labour, and have food at will, they enjoy their full physical-necessary. They are then in the height of beauty, and enjoy the greatest degree of happiness they are capable of. Animals which are forced to labour, prove to us very plainly, that this _physical-necessary_ is not fixed to a point, but that it may vary like most other things: every one perceives the difference between labouring cattle which are well fed, and those which are middling, or ill fed; all however, I suppose to live in health, and to work according to their strength. This represents the nature of a _physical-necessary_ for man. In many of the inferior classes in every nation, we find various degrees of ease among the individuals; and yet upon the whole, it would be hard to determine, which are those who enjoy superfluity; which are those who possess the pure physical-necessary; and which are those who fall below it. The cause of this ambiguity must here be explained. The nature of man furnishes him with some desires relative to his wants, which do not proceed from his animal oeconomy, but which are entirely similar to them in their effects. These proceed from the affections of his mind, are formed by habit and education, and when once _regularly established_, create another kind of necessary, which, for the sake of distinction, I shall call _political_. The similitude between these two species of _necessary_, is therefore the cause of ambiguity. This _political-necessary_ has for its object, certain articles of _physical superfluity_, which distinguishes what we call _rank_ in society. _Rank_ is determined by birth, education, or habit. A man with difficulty submits to descend from a higher way of living to a lower; and when an accidental circumstance has raised him for a while, above the level of that _rank_ where his _birth_ or _education_ had placed him, his ambition prompts him to support himself in his elevation. If his attempt be a rational scheme, he is generally approved of; the common consent of his fellow-citizens prescribes a certain _political-necessary_ for him, proportioned to his ambition; and when at any time _this_ comes to fail, he is considered to be in want. If on the other hand, a person either from vanity, or from no rational prospect of success, forms a scheme of rising above the _rank_ where _birth_ or _education_ had placed him, his fellow-citizens do not consent to prescribe for him a political-necessary suitable to his ambition; and when this fails him, he is only considered to fall back into the class he properly belonged to. But if the political-necessary suitable to this rank should come to fail, then he is supposed to be deprived of his _political-necessary_.