[33] For as the master of a ship collects together all the means which may tend to ensure him a favourable voyage with reference to and in dependency on the changes of the wind, not always guiding his vessel in one and the same way; and as a physician does not apply one and the same means of cure to every sick person, nor even to one person if his disease varies in its character, but watches the periods of its abatement, and of its intensity, and of its becoming full or empty, and the alterations of the causes of the sickness, and so varies his remedies as much as possible to secure the safety of his patient, applying one remedy at one time and another at another;