Man doth what he can, and God what He will.

People may apply effort, skill, and judgment, yet the final course of events is understood to rest with divine will. The saying counsels humility about the limits of personal control.

It can also express resignation after all reasonable action has been taken, separating human responsibility for action from God's authority over results. This is a specifically theistic framing, not a claim intended to fit secular or differently religious views.

Use it in a religious or reflective setting when someone has done all they reasonably can but cannot control what follows. It may offer consolation or encourage humility about an uncertain outcome. Its older wording can sound formal or archaic in ordinary contemporary conversation.