In the mid 1800s, the labor theory of value ("the value of a commodity is equal to the labor necessary to produce it") was largely accepted among political economists; but they were unable to answer the question: "Where, then, does profit come from?" When Marx answered this question with his discovery of labor-power and surplus value, not only did it generate outrage against his discovery, but the outrage then extended back to the labor theory of value itself, which became associated with his name.
I can't help but wonder how often this has happened in the scientific community.
Anyway, let me finish with a quotation: "Man may be excused for feeling some pride in having risen, though not through his own exertions, to the very summit of the organic scale; and the fact of his having thus risen, instead of having been aboriginally placed there, may give him hope for a still higher destiny in the far future." -- Charles Darwin, 1871
