In traditional Japanese fencing there were three acceptable outcomes to a duel. Katsu or victory, make or defeat, or ai uchi mutual killing. Ai uchi is, in reality, the highest level of combat. It is only against a greatly inferior opponent that you will either be able to strike first or be able to block and then strike. Generally you and your opponent will strike at the same time, and your will and your destiny will determine the outcome. With successful ai uchi you do not block the attack, you, in reality, block his body through your attack, suppressing the attack. None of these outcomes were favored over the other.