2. Another distinction may be gathered from St. Thomas (1a 2æ, q. 21, art. 2, ad 2), that the special intellectual habit called _art_ disposes a man to act correctly towards some particular end, but a moral habit towards the common end, scope and purpose of all human life. Thus medical skill ministers to the particular end of healing: while the moral habit of temperance serves the general end, which is final happiness and perfection. So to give a wrong prescription through sheer antecedent ignorance, is to fail as a doctor: but to get drunk wittingly and knowingly is to fail as a man. 3. The grand distinction between intellectual and moral habits seems to be this, that moral habits reside in powers which may act against the dictate of the understanding,--the error of Socrates, noticed above (c. v., s. ii., n. 2, p. 70), lay in supposing that they could not so act: whereas the power which is the seat of the intellectual habits, the understanding, cannot possibly act against itself. Habits dispose the subject to elicit acts of the power wherein they reside. Moral habits induce acts of will and sensitive appetite: intellectual habits, acts of intellect. Will and appetite may act against what the agent knows to be best: but intellect cannot contradict intellect. It cannot judge that to be true and beautiful which it knows to be false and foul. If a musician strikes discords on purpose, or a grammarian makes solecisms wilfully, he is not therein contradicting the intellectual habit within him, for it is the office of such a habit to aid the intellect to judge correctly, and the intellect here does correctly judge the effect produced. On the other hand, if the musician or grammarian blunders, the intellect within him has not been contradicted, seeing that he knew no better: the habit of grammar or music has not been violated, but has failed to cover the case. Therefore the intellectual habit is not a safeguard to keep a man from going against his intelligent self. No such safeguard is needed: the thing is impossible, in the region of pure intellect. In a region where no temptation could enter, intellectual habits would suffice alone of themselves to make a perfectly virtuous man. To avoid evil and choose good, it would be enough to know the one and the other. But in this world seductive reasonings sway the will, and fits of passion the sensitive appetite, prompting the one and the other to rise up and break away from what the intellect knows all along to be the true good of man. Unless moral virtue be there to hold these powers to their allegiance, they will frequently disobey the understanding. Such disobedience is more irrational than any mere intellectual error. In an error purely intellectual, where the will has no part, the objective truth indeed is missed, but the intelligence that dwells within the man is not flouted and gain-sayed. It takes two to make a contradiction as to make a quarrel. But an intellectual error has only one side.