When I was a philosophy major in college, I was a bit disdainful of history. No, I am not talking about the philosophy of history, but real history.
If the truths that are being espoused are valid, they are universal. As such the historical context should not matter. This is how I thought.
Now, older, a new love of history rounds out what I learned in philosophy, and creates a fuller understanding of what each figure is speaking of. So, my advice - read and love history.
Who did the founding fathers turn to when creating this country ? Plutarch, not Plato