A more thorough explanation:

Definition: According to the subject matter.

Example: A legal case is decided secundum materiam subjectam, meaning the decision is based on the specific facts and circumstances of the case.

This term is often used in legal contexts to emphasize the importance of considering the specific details of a case when making a decision. It reminds us that each case is unique and should be evaluated on its own merits.

Definition: According to nature.

Example: The philosopher Aristotle believed that living according to reason and virtue was living secundum naturam, or in accordance with our natural state.

This term is often used in philosophical and ethical discussions to describe actions or behaviors that are in line with our inherent nature as human beings. It suggests that there is a natural order to things that we should strive to follow in order to live a fulfilling and virtuous life.