Aethra guided Theseus to a forest clearing, in the midst of which was a boulder. Theseus proceeded to lift the stone easily, or so the myth is often told. But Theseus would have had trouble with a task involving brute strength. This may be deduced from the tradition that he invented "scientific" wrestling, the discipline by which even a lightweight can beat a stronger adversary by fancy footwork, trick holds and using the opponent's momentum to advantage. Theseus would have had little cause to invent such tactics if he'd been capable of beating his adversaries by sheer physical strength. So when it came to lifting boulders, he was at a disadvantage. Resourcefulness, another heroic trait, must have come to his aid. He would have looked about for some means to multiply his physical strength.