When it is impossible to obtain good tools, the next best thing is to understand thoroughly the defects of those we have.
 John Stuart Mill, A System Of Logic, Ratiocinative And Inductive (1843). copy citation

Context

“sufficient variety of precise words fitted to express them, there should be no practice to which even scientific thinkers are more addicted than that of taking valuable words to express ideas which are sufficiently expressed by other words already appropriated to them. When it is impossible to obtain good tools, the next best thing is to understand thoroughly the defects of those we have. I have therefore warned the reader of the ambiguity of the names which, for want of better, I am necessitated to employ. It must now be the writer's endeavor so to employ them as in no case to leave the meaning doubtful or obscure.” source