When the close of active professional exertions is felt to be approaching, and the pressure of that period "aut jam urgentis aut certe adventantis senectutis" becomes perceptible, a natural wish arises in the mind of any man who has been especially engaged in what he regards as a good and useful work to leave the work, if not finished, yet secure; or if not yet secure, at least advanced by his labours, and as little incomplete as the shortness of his life, and the limitation of his opportunities, permit.