四分律刪繁補闕行事鈔 2.367

2.367

何故須二者？若唯制無開，中下施分，進道莫由；若唯開無制，上行慢求，息於自勵，故須二教，攝生義足。今分二教，攝法分齊；止持作犯，唯對二教中事以明；作持止犯，通對二教法、事兩種。所以前不通法者，法唯進修方知；事但離過自攝，故得明也。

Why are both necessary? If there were only prescription without allowance, the medium and inferior capacities would have no share, and there would be no way to advance on the path; if there were only allowance without prescription, those of superior practice would become negligent and greedy, resting from self-exertion. Therefore both teachings are necessary, so that the meaning of gathering sentient beings is sufficient. Now, dividing the two teachings demarcates the scope of gathering dharmas: observance by abstention and transgression by action are clarified solely in reference to practical matters within the two teachings; observance by action and transgression by abstention generally refer to both dharmas and practical matters within the two teachings. As for why the former does not encompass dharmas: dharmas are known only by advancing in cultivation; practical matters only require leaving faults behind to restrain oneself; hence they can be clarified.