Models are undeniably beautiful, and a man may justly be proud to be seen in their company. But they may have their hidden vices. The question is, after all, not only whether they are good to look at, but whether we can live happily with them.
— A Kaplan, The conduct of enquiry (As quoted in Rutherford Aris’ Mathematical modelling techniques
I think but for the sexist language in the first sentence (which, I would have preferred, if read, “a person” instead of “a man”), it is a great quote. While we are on the topic, this quote from Feynman’s Nobel lecture about falling in love with one’s own theory is also a good one:
… the idea seemed so obvious to me and so elegant that I fell deeply in love with it. And, like falling in love with a woman, it is only possible if you do not know much about her, so you cannot see her faults. The faults will become apparent later, but after the love is strong enough to hold you to her. So, I was held to this theory, in spite of all difficulties, by my youthful enthusiasm.