"[T]he reason why human understanding has been able to advance in the past, and may do so in the future, is that true insights are cumulative and retain their value regardless of what happens to their discoverers; while fads and stunts may bring an immediate profit to the impresarios, but lead nowhere in the long run, cancel each other out, and are dropped as soon as their promoters are no longer there (or have lost the power) to direct the show. Anyway, let us not despair."