He seemed to have a particular affinity for the Roman Stoic philosopher, statesman, dramatist, and humorist Seneca. He quotes him no less than 4 or 5 times in this work. It is a delightful and significant thing to be reading a highly practical Puritan exposition of Christian contentment and suddenly find him pause with a helpful illustration, “I remember reading in Senca…”.
You will also find references to various statesmen, philosophers, and literary types from antiquity: Cato, Plutarch, Solon, Socrates. Antisthenes, etc.
You can’t make the blanket claim that the Puritans, as a whole, had tunnel vision in their studies. I think such a claim could be far more fairly levied and more easily justified against some of their modern heirs.