The second barrier he described as too steep a study gradient, and explained in terms of attempting to master a skill without having grasped a necessary previous step. By way of example, he offers the student driver unable to coordinate hands and feet to manually shift the gears of a moving vehicle. Although one would imagine the difficulty to lie with the act of shifting, in fact there is some earlier unmastered skill, perhaps simply keeping the vehicle on the road. In either case, the solution is simply a matter of cutting back, determining what the student had last understood and then isolating what earlier step had been neglected. Again, the reaction to skipping a gradient is both pronounced and physiological, and includes a confusion or “reelingness” that is frequently misidentified and so proves the ruin of many an otherwise capable student.