matter of course

crash course

A quick, intense course of learning, especially one which is informal or hurried.

due course

Regular or appropriate passage or occurrence

grey matter

Brains; a person's ability to think.

let nature take its course

To permit events to proceed or a situation to develop without intervention or interference.

matter at hand

The current issue, which requires immediate attention.

matter of life and death

An extremely urgent matter.

matter of time

An inevitable result; something that is bound to happen.

par for the course

To be expected; normal; common.