But the great tragedy of Science — the slaying of a beautiful hypothesis by an ugly fact — which is so constantly being enacted under the eyes of philosophers...

T. H. Huxley (1825–1895), Darwin’s prominent defender and a leading Victorian advocate of scientific naturalism, used this line while emphasizing the discipline of science: hypotheses must remain provisional and answerable to observation. The remark belongs to his public-facing style—witty, combative, and pedagogical—aimed at explaining to educated lay audiences how scientific knowledge advances through testing and correction rather than through reverence for elegant theories. In the late nineteenth century, as debates over evolution, geology, and biblical authority sharpened, Huxley repeatedly stressed that science progresses by submitting even cherished ideas to “the tribunal of fact,” a stance that also served his broader campaign for scientific education and intellectual honesty.

Huxley frames scientific progress as a recurring “tragedy”: the emotional and intellectual disappointment of seeing a pleasing, coherent theory overturned by stubborn evidence. The metaphor underscores a core norm of science—facts, not aesthetic appeal or philosophical preference, decide. Calling the fact “ugly” highlights that reality can be messy, counterintuitive, or resistant to neat explanation, while “beautiful hypothesis” acknowledges the genuine allure of elegant models. The line also functions as a warning against dogmatism: attachment to one’s own explanatory schemes is natural, but scientific integrity requires welcoming refutation as the mechanism by which knowledge becomes more reliable.

1) “The great tragedy of science—the slaying of a beautiful hypothesis by an ugly fact.”
2) “The tragedy of science is the murder of a beautiful theory by a brutal fact.”
3) “A beautiful hypothesis slain by an ugly fact.”