Content Warning: This section discusses scientific racism.

Throughout Letters to a Young Scientist, Wilson takes many opportunities to describe the qualities that successful scientists should possess. In part, this is to provide a kind of template for young aspiring scientists, so that they can measure their own traits and qualities and see if they have what it takes to pursue a career in science. It is also a way for Wilson to break down certain prevailing ideas about what a scientist is like.

Even those who think they are not suited to science could succeed. For example, Wilson is very careful to banish the idea that all scientists must be mathematically minded. He sees a fear of mathematics as one of the primary reasons that aspiring scientists turn away from committing to the field. He hopes that by highlighting his own shortcomings in math, he can persuade those who are not mathematically inclined to pursue a scientific career. His solution to lacking a mathematical brain is to collaborate with mathematicians when necessary.

Wilson argues that scientists should be ambitious and passionate, for passion and drive are what inspire lifelong careers that produce important and groundbreaking scientific discoveries. Wilson uses his own long-lasting interest in insects as an example of passion and urges young scientists to cultivate their scientific interests because they will certainly lead to fulfilling and worthwhile careers.