You have come out of the trees so recently, and your kinship with the monkeys and lemurs is still so strong, that you tend toward abstraction without being able to part with the palpable—firsthand experience. Therefore a lecture unsupported by strong sensuality, full of formulas telling more about stone than a stone glimpsed, licked, and fingered will tell you—such a lecture will either bore you and frighten you away, or at the very least leave a certain unsatisfied need familiar even to lofty theoreticians, your highest class of abstractors, as attested by countless examples lifted from scientists’ intimate confessions, since the vast majority of them admit that, in the course of constructing abstract proofs, they feel an immense need for the support of things tangible.