Next we must form an estimate of the matter which we mean to deal with, and compare our strength with the deed we are about to attempt: for the bearer ought always to be more powerful than his load: indeed, loads which are too heavy for their bearer must of necessity crush him: some affairs also are not so important in themselves as they are prolific and lead to much more business, which employments, as they involve us in new and various forms of work, ought to be refused. Neither should you engage in anything from which you are not free to retreat: apply yourself to something which you can finish, or at any rate can hope to finish: you had better not meddle with those operations which grow in importance, while they are being transacted, and which will not stop where you intended them to stop.