Those who, in debate, appeal to their qualifications, argue from memory, not from understanding. - Leonardo da Vinci

The vine that has grown old on an old tree falls with the ruin of that tree, and through that bad companionship must perish with it.

Ask counsel of him who rules himself well.

A picture or representation of human figures, ought to be done in such a way as that the spectator may easily recognise, by means of their attitudes, the purpose in their minds. Thus, if you have to represent a man of noble character in the act of speaking, let his gestures be such as naturally accompany good words; and, in the same way, if you wish to depict a man of a brutal nature, give him fierce movements; as with his arms flung out towards the listener, and his head and breast thrust forward beyond his feet, as if following the speaker's hands. Thus it is with a deaf and dumb person who, when he sees two men in conversation — although he is deprived of hearing — can nevertheless understand, from the attitudes and gestures of the speakers, the nature of their discussion.