It helps not our ignorance to feign a knowledge where we have none, by making a noise with sounds, without clear and distinct significations.
 John Locke, An Essay Concerning Human Understanding (1689). copy citation

Context

“nor shall be ashamed to own my ignorance, till they that ask show me a clear distinct idea of substance. 18. Different meanings of substance. I endeavour as much as I can to deliver myself from those fallacies which we are apt to put upon ourselves, by taking words for things. It helps not our ignorance to feign a knowledge where we have none, by making a noise with sounds, without clear and distinct significations. Names made at pleasure, neither alter the nature of things, nor make us understand them, but as they are signs of and stand for determined ideas. And I desire those who lay so much stress on the sound of these two syllables, SUBSTANCE, to consider whether applying it, as they do, to the infinite, incomprehensible God, to finite spirits, and to body, it be in the same sense;” source