The longitudinal arch is the strongest part of our foot. Falling straight down through the talus optimizes the power of the arch, enabling us to use its full strength. This is an essential aspect of innate uprighting. The arch is elevated, with only two points touching the ground -- the pivot point on the heel and the ball of the big toe (here, I refer to the two small sesamoid bones on the big toe, together, as one point of contact). In between these two points there is absolutely no ground contact.