Source: p 87, Philosophy ; A Very Short Introduction (2002) by Edward Craig.
Charles Darwin: The Origin of Species
The first thing we can learn from this fascinating book is not to bother too much about drawing a neat sharp line between philosophy and science.
[1.] The point is not that the line isn’t sharp, although I believe that to be true.
[2.] The point is that the line (if it exists) is not of much importance for philosophy.
On any reasonable way of drawing it Darwin’s Origin is science, more specifically biology. But because of its subject-matter, and the claims it makes, very few books have had greater philosophical impact. For it implies a startling thesis about us and how we have come to be as we are. It may not startle us today, but it startled most of his contemporaries to the point of shock; and there are still a number of people trying to perform the difficult balancing act of rejecting it without appearing merely ignorant and prejudiced.
Central Question: Why is the bolded true?
To me, [1.] (belief in the line's sharpness) contradicts [2.] (disbelief of the line's importance), because if a line between science and philosophy really matters not for philosophy, then: why is there a line at all, and why did the natural sciences (and maths and other independent subjects now) separate from philosophy?