Book XII · 6

Practise thyself even in the things which thou despairest of accomplishing. For even the left hand, which is ineffectual for all other things for want of practice, holds the bridle more vigorously than the right hand; for it has been practised in this.

Practise that also wherein thou hast no expectation of success. For even the left hand, which for every other function is inefficient by reason of a want of practice, has yet a firmer grip of the bridle than the right. For it has had practice in this.