Argument lacks power to take effect when urged by men whose strength is less than their desire

Argument lacks power to take effect when urged by men whose strength is less than their desire. Demades. On the Twelve Years. Speech 1. Section 29.

Image: Black-figured ceramic depicting two boxers and a referee, Greek, 7th-5th century BCE courtesy of Wikimedia Commons contributor כ.אלון (digitally enhanced) Note: I selected this image because, to me, an argument is verbal sparring, much like its physical counterpart.