It is so in any particular pursuit, from the manufacturing of pins to the construction of philosophical systems. Every individual can exert that quantity of mind necessary to his wants and adapted to his situation; the quality of pleasure is nothing in the present question: for I think that we are mistaken concerning the gradations of human felicity. It does at first appear, that an astronomer rapt in abstraction, while he gazes on a star, must feel a more exquisite delight than a farmer who is conducting his team; or a poet experience a higher gratification in modulating verses than a trader in arranging sums. But the happiness of the ploughman and the trader may be as satisfactory as that of the astronomer and the poet. Our mind can only he conversant with those sensations which surround us, and possessing the skill of managing them, we can form an artificial felicity; it is certain that what the soul does not feel, no more affects it than what the eye does not see. It is thus that the trader, habituated to humble pursuits, can never be unhappy because he is not the general of an army; for this idea of felicity he has never received. The philosopher who gives his entire years to the elevated pursuits of mind, is never unhappy because he is not in possession of an Indian opulence, for the idea of accumulating this exotic splendour has never entered the range of his combinations. Nature, an impartial mother, renders felicity as perfect in the school-boy who scourges his top, as in the astronomer who regulates his star. The thing contained can only be equal to the container; a full glass is as full as a full bottle; and a human soul may be as much satisfied in the lowest of human beings as in the highest. In the progress of an individual pursuit, what philosophers call the associating or suggesting idea is ever busied, and in its beautiful effects genius is most deeply concerned; for besides those trains of thought the great artist falls into during his actual composition, a distinct habit accompanies real genius through life in the activity of his associating idea, when not at his work; it is at all times pressing and conducting his spontaneous thoughts, and every object which suggests them, however apparently trivial or unconnected towards itself, making what it wills its own, while instinctively it seems inattentive to whatever has no tendency to its own purposes. Many peculiar advantages attend the cultivation of one master passion or occupation. In superior minds it is a sovereign that exiles others, and in inferior minds it enfeebles pernicious propensities. It may render us useful to our fellow-citizens, and it imparts the most perfect independence to ourselves. It is observed by a great mathematician, that a geometrician would not be unhappy in a desert.