Let's imagine that a Greek Philosopher, A, proposed a theory of matter that bares a striking resemblance to what contemporary experiments suggest is the case. The arguments for her theory, however, were at best dubious even by the standards of her time. Has A done enough to earn philosophical or scientific credit for the theory? To put it another way, how do we draw the line between lucky speculation and genuine insight in the history of ideas? Does such a line make a difference?