Study the Masters
Study the masters, not their pupils is one of those bits of pedagogical advice more honored in the breach than in the observance. Usually we have good excuses, of course: their notation is obsolete and obscure, or they wrote in Latin, or the literature is too scattered - all true and reasonable.
There are happy exceptions. The principal textbooks in string theory carry the names of some of it's greatest masters: Green, Schwarz, Witten, Polchinski. Rarely read, though, are older works by Newton, Maxwell, and Rayleigh.
A couple of groups of students have no excuse though. Charles Darwin's Origin of Species is almost entirely modern a century and a half later, and it's a model of lucidity of thought and expression. Equally remarkable is Adam Smith's The Wealth of Nations two and a quarter centuries downstream in time. Each laid out the foundations of his science with great clarity and prescience. I'm sure that many undergraduate majors in biology and economics escape reading these books, though, and graduates too. They really shouldn't.