לע"נ סבי ר' אלכסנדר זושא בן ר' יוסף
We are all familiar with the notion that one should learn Torah lishmah - with no ulterior motives. But there is another parallel concept: One must learn secular wisdoms shelo lishmah - WITH ulterior motives. If one learns other wisdoms lishmah then he extinguishes the light of Torah within him.
Why is this? When one learns Torah for honor or semicha [i.e. Masters degree in Rabbinics so he can make a living off it] or other non-pure reasons, these motivations don't relate to his cognitive faculties but to other realms. Therefore, even such learning is valuable and has the capacity to eventually bring him to lishmah. His intention is to eventually reach a state of lishmah and in the meantime he has other non-cognitive intentions which don't relate to the place where the actual learning takes place i.e. the mind.
However, if one learns math or English Literature lishmah then in his mind there is a perfection in the world that exists outside of Torah. THAT extinguishes the light of Torah.
So learn your Torah lishmah or at least shelo lishmah with intention to achieve lishmah. And learn your American history shelo lishmah. Make sure that your cognitive faculties are attuned to the limitless, eternal importance of Torah and the limited, utilitarian value of secular wisdoms.