 By the time Hume began to write the Treatise three years later, he had immersed himself in the works of the modern philosophers, but found them disturbing, not least because they made the same mistakes the ancients did, while professing to avoid them. Why, Hume asks, haven’t philosophers been able to make the spectacular progress in understanding human nature that natural philosophers—whom we now call “scientists”—have recently achieved in the physical sciences? His answer is that while scientists have cured themselves of their “passion for hypotheses and systems”, philosophers haven’t yet purged themselves of this temptation. Their theories were too speculative, relied on a priori assumptions, and paid too little attention to what human nature is actually like. Instead of helping us understand ourselves, modern philosophers were mired in interminable disputes—evident even to “the rabble without doors”—giving rise to “the common prejudice against metaphysical reasonings of all kinds”, that is, “every kind of argument which is in any way abstruse, and requires some attention to be comprehended” (T xiv.3).