The martyr sacrifices herself (himself in a few instances) entirely in vain. Or rather not in vain; for she (or he) makes the selfish more selfish, the lazy more lazy, the narrow narrower.
Letter, c. 1867, to Benjamin Jowett. Source: Forever Yours, Florence Nightingale: Selected Letters, ch. 4 (1989). Quoted from: The Columbia World of Quotations, 1996