It is moreover extremely indecent to spit, cough, and expectorate (as it were) in company, as some hearty fellows are apt to do: and more so, when yo… - Giovanni della Casa

For tho' it is certainly more laudable, and a thing of greater moment, to be generous, constant, and magnanimous, than merely to be polite and well bred; yet we find, from daily experience, that sweetness of manners, a genteel carriage, and, polite address are frequently of more advantage to those who are so happy as to be possessed of them, than any greatness of soul or brightness of parts are to those who are adorned with those more shining talents. For those slighter accomplishments are of more frequent, or rather of constant and daily use on every occasion; as we are under a necessity of conversing daily with other people: Whereas justice, fortitude, and those other more exalted virtues, are of much less frequent occurrence. For neither is a generous or a brave man obliged to exhibit those virtues, every hour of the day (which indeed would be impossible,) neither has a wise man, or a man of great genius, an opportunity of displaying those extraordinary talents, but very rarely. As much therefore as those greater qualities exceed those more trifling accomplishments in weight and importance; so much the latter exceed the former in number and more frequent use.

These kinds of habits, in good company, are so very nauseous and disgusting, that if we indulge ourselves in them, no one can be very fond of our acquaintance. So far from it, that even those, who are inclined to wish us well, must, by these and the like disagreeable customs, be entirely alienated from us.— Those ill-bred people, who expect their acquaintance to love and caress them, with all their foibles, are as absurd as a poor ragged cinder-wench; who should roll about upon an heap of ashes, scrabbling and throwing dust in the face of every one that passed by; and yet flatter herself that she should allure some youth to her embraces, by these dirty endearments; which would infallibly keep him at a distance.

You ought to regulate your manner of behaviour towards others, not according to your own humour, but agreeably to the pleasure and inclination of those with whom you converse.