Line of Attack
The line of attack is the line connecting the attack and the target. For example, in a punch to the face, the line from the fist to the face is the line of attack. Fundamental techniques emphasize moving off the line of attack to apply the defense. Advanced techniques include redirecting and controlling the line of attack. We want to avoid the direct energy of an attack instead of stopping that energy.
Blending with the Energy
Blending with an attack means to match the energy of the attack instead of conflicting with it. It's similar to when you push open a swinging door and someone on the other side pulls open the door at the exact time. If the timing is just right, you may feel like you just fell through the door. Sometimes, the blend occurs without the attacker even realizing it. Uniting with the energy of the attack allows us to take control and redirect that energy to an appropriate outcome.
Taking the Balance
Aikido techniques work by upsetting the balance of the attacker such that they cannot regain their balance. We call this "taking the balance" of the attacker.
An object is stable when its center of gravity is over its base of support. It is very stable when it has a low center of gravity and wide base of support. This simple fact is key to understanding how Aikido techniques work.
Aikido techniques disrupt the attacker's stability by moving their center of gravity so that it is no longer over their base of support. This is accomplished with a combination of drawing the attacker's center out, raising the attacker's center of gravity, reducing the attacker's base of support, and restricting the attacker's ability to regain balance.
It is through proper technique and timing, not strength, that make Aikido an effective self-defense.