The names of such things as affect us, that is, which please, and displease us, because all men be not alike affected with the same thing, nor the same man at all times, are in the common discourses of men of inconstant signification. For seeing all names are imposed to signifie our conceptions; and all our affections are but conceptions; when we conceive the same things differently, we can hardly avoyd different naming of them. For though the nature of what we conceive, be the same; yet the diversity of our reception of it, in respect of different constitutions of body, and prejudices of opinion, gives everything a tincture of our different passions. And therefore in reasoning, a man must take heed of words; which besides the signification of what we imagine of their nature, have a signification also of the nature, disposition, and interest of the speaker; such as are the names of Vertues, and Vices; For one man calleth Wisdome, what another calleth feare; and one cruelty, what another justice; one prodigality, what another magnanimity; and one gravity, what another stupidity, &c. And therefore such names can never be true grounds of any ratiocination. No more can Metaphors, and Tropes of speech: but these are less dangerous, because they profess their inconstancy; which the other do not.
Thomas Hobbes, Leviathan, Part 1: Of Man, section 4: Of Speech