3. A true work of art cannot be added to or taken from without spoiling it. A perfect church would be spoiled by a lengthening of the chancel or raising the tower, albeit there are buildings, secular and ecclesiastical, that might be drawn out two miles long and not look any worse. The colouring of a picture must not be too violent and positive; but artistic colouring must be chaste, and artistic utterance gentle, and artistic action calm and indicative of self-command. Not that voice and action should not be impassioned for a great emergency, but the very passion should bear the mark of control: in the great master's phrase, you must not "tear a passion to tatters." It is by moderation sitting upon power that works of art truly masculine and mighty are produced; and by this sign they are marked off from the lower host of things, gorgeous and redundant, and still more from the order of "the loose, the lawless, the exaggerated, the insolent, and the profane." 4. On these considerations Aristotle framed his celebrated definition of moral virtue: _the habit of fixing the choice in the golden mean in relation to ourselves, defined by reason, as a prudent man would define it_. All virtue is a _habit_, as we have seen--a habit of doing that which is the proper act of the power wherein the habit resides. One class of moral virtues is resident in the will, the act of which power is properly called _choice_. The rest of the moral virtues reside in the sensitive appetite, which also may be said to _choose_ that object on which it fastens. Thus moral virtue is a habit of _fixing the choice_. The _golden mean_ between two extremes of excess and defect respectively has been already explained, and may be further shown by a review of the virtues. Besides fortitude and temperance, already described, _liberality_ is a mean between prodigality and stinginess; _magnificence_ between vulgar display and pettiness: _magnanimity_ between vainglory and pusillanimity; _truthfulness_ between exaggeration and dissimulation; _friendship_ between complaisance, or flattery, and frowardness,--and so of the rest. The golden mean must be taken _in relation to ourselves_, because in many matters of behaviour and the management of the passions the right amount for one person would be excessive for another, according to varieties of age, sex, station, and disposition. Thus anger that might become a layman might be unbefitting in a churchman; and a man might be thought loquacious if he talked as much as a discreet matron. [Footnote 5] The golden mean, then, must be _defined by reason_ according to the particular circumstances of each case. But as Reason herself is to seek where she is not guided by Prudence, the mean of virtue must be defined, not by the reason of the buffoon Pantolabus, or of Nomentanus the spendthrift, but _as a prudent man_ would define it, given an insight into the case.