Therefore the task of the painter in his pursuit of ideal form is to attain accurate knowledge, so far as may be in his power, of the character, habits, and peculiar virtues and duties of every species of being; down even to the stone, for there is an ideality of stones according to their kind, an ideality of granite and slate and marble, and it is in the utmost and most exalted exhibition of such individual character, order, and use, that all ideality of art consists. The more cautious he is in assigning the right species of moss to its favorite trunk, and the right kind of weed to its necessary stone, in marking the definite and characteristic leaf, blossom, seed, fracture, color, and inward anatomy of everything, the more truly ideal his work becomes. All confusion of species, all careless rendering of character, all unnatural and arbitrary association, is vulgar and unideal in proportion to its degree. Sec. 14. How connected with the imaginative faculties. It is to be noted, however, that nature sometimes in a measure herself conceals these generic differences, and that when she displays them it is commonly on a scale too small for human hand to follow. The pursuit and seizure of the generic differences in their concealment, and the display of them on a larger and more palpable scale, is one of the wholesome and healthy operations of the imagination of which we are presently to speak.[37] Generic differences being commonly exhibited by art in different manner and way from that of their natural occurrence, are in this respect more strictly and truly ideal in art than in reality. Sec. 15. Ideality, how belonging to ages and conditions. This only remains to be noted, that, of all creatures whose existence involves birth, progress, and dissolution, ideality is predicable all through their existence, so that they be perfect with reference to their supposed period of being. Thus there is an ideal of infancy, of youth, of old age, of death, and of decay. But when the ideal form of the species is spoken of or conceived in general terms, the form is understood to be of that period when the generic attributes are perfectly developed, and previous to the commencement of their decline. At which period all the characters of vital and typical beauty are commonly most concentrated in them, though the arrangement and proportion of these characters varies at different periods, youth having more of the vigorous beauty, and age of the reposing; youth of typical outward fairness, and age of expanded and etherealized moral expression; the babe, again, in some measure atoning in gracefulness for its want of strength, so that the balanced glory of the creature continues in solemn interchange, perhaps even "Filling more and more with crystal light, As pensive evening deepens into night."