If we set aside personal edification, what reasons remain for a philosopher of science to study the intellectual biography of a famous (or infamous) scientist? This question raises familiar and perhaps tired arguments about the relationship between history of science and philosophy of science, but it is also practical: why take the time to digest almost 600 pages devoted to the controversial German zoologist Ernst Haeckel? A preliminary answer is the author. The historical investigations of Robert Richards have been of ongoing interest to philosophers, whether it be evolutionary explanations of mind and behavior in the nineteenth century (Dennett 1989) or his contentious claims-reinvigorated in the present volume-about Darwin's commitment to embryonic recapitulation (Lennox 1994). Richards has a knack for unearthing details germane to conceptual reflection, in no small part because of his own philosophical predilections (e.g., a selection model of scientific theory development). Here I entertain three more reasons to follow the injunction tolle lege: the prescient synthesis exemplified in Haeckel's evolutionary theorizing, the impact of model organism choice, and the critical role of pictures in scientific reasoning accented by Haeckel's artistic proclivities.