He that hath many irons in the fire, some of them will cool.

A person who takes on too many jobs, plans, or commitments at once cannot give each one enough attention. Some efforts may be neglected, lose momentum, or remain unfinished before they can be completed.

The saying advises moderation in accepting work and setting priorities. It suggests that activity and ambition alone are not enough when divided attention prevents promising tasks from receiving the care they need.

Use it to warn against overcommitment when someone is pursuing several projects or obligations at once. Its metalworking image suits reflective advice about capacity and priorities; because the wording is archaic, a contemporary paraphrase may be clearer for general audiences.