From Plié.txt: grand plié or full bending of the knees (the knees should be bent until the thighs are horizontal)... When a grand plié is executed in either the first, third or fourth position croisé (feet in the fifth position but separated by the space of one foot) or the fifth position, the heels always rise off the ground and are lowered again as the knees straighten. The bending movement should be gradual and free from jerks, and the knees should be at least half-bent before the heels are allowed to rise. The body should rise at the same speed at which it descended, pressing the heels into the floor. In the grand plié in the second position or the fourth position ouverte (feet in the first position but separated by the space of one foot) the heels do not rise off the ground.