I couldn't find any specific information about David Goodman making that statement or its context, so I can't provide a definitive answer on what he may have meant. However, based on the information you provided, it seems that he might be referring to the dedication and importance of studying statistical mechanics, even in the face of personal struggles or tragedies.
Ludwig Boltzmann and Paul Ehrenfest were prominent physicists who made significant contributions to the field of statistical mechanics. The mention of their deaths by their own hands may suggest that they faced personal challenges or mental health issues. Despite their unfortunate fates, their work and dedication to studying statistical mechanics remained influential and important.
Therefore, when David Goodman says, "Now it is our turn to study statistical mechanics," he could be implying that they should continue the legacy of Boltzmann and Ehrenfest by dedicating themselves to the study of statistical mechanics, regardless of any personal hardships they may encounter. It might be a call to persevere, learn from the past, and contribute to the field in a meaningful way.