Newton stated his second law in terms of momentum, calling momentum the:

1. The importance of momentum was recognised early in the development of classical physics. 2. It was recognised much earlier than the importance of energy. 3. Momentum was deemed so important that it was called the quantity of motion. 4. Newton actually stated his second law of motion in terms of momentum. _Source: OpenStax College Physics for AP(R) Courses 2e (CC BY 4.0), Ch 8 'Linear Momentum and Collisions', sections 8.1-8.7_