I hope it will be easy, by the preceding and the following directions, for any man of sense, not vers’d at all in physic, to know the state of his own health precisely: and ’tis a most important knowledge. Hippocrates, who knew physic better than all who have followed him, declares it to be an easy science, tho’ it requires length of time to learn it; and Boerhaave, the Hippocrates of our succeeding times, lectur’d for ever publicly on the simplicity and ease of physic. They perplex themselves who think it difficult: only let the plain considerate man attend to what he feels, and believe what is here told him will result from it; then he may keep his mind at peace, which is a great ingredient in the health of the body: but this full credit is necessary; for the origin of his disorders is often very distant from their apparent effects. Hitherto we have treated of the condition of persons advanced in years, who are healthy: and the rules we have laid down are for preserving and continuing that state: and he who observes them duly cannot well fail of success. We now shall consider the several more frequent faults of the constitution at this period of life; and the diseases arising from them. The old man may be so far his own doctor, as to amend the general distemperature of his body; and often he may prevent those diseases: but if he fall into them, whether by neglect of these cautions, or in spite of their force, let him then call in a physician. We can advise him how to preserve health when he has it; and how to remedy general disorders, so as to prevent more particular ones; so far as a due regimen may do that: but he is a very ill judge of the human frame, who will pretend to remedy its diseases without a knowledge both of its structure, and of the qualities of remedies: and he would be a bad member of society who gave such advice to any. It were as easy to teach some other art by writing; and as rational to attempt making a watchmaker, or a shipbuilder, by a description of the tools. The whole life of a physician, spent in attention and experience, hardly qualifies him for the undertaking: how then should a few light words give sufficient information? CHAP. XI. _Of a fulness of blood._ An overfulness of blood naturally brings on a redundance of the other humours: for as they are separated from the blood, they naturally encrease with it in quantity. The one or the other of these excesses may, and naturally will, occasion disorders; much more both. The old man may know when he has too much blood in his veins from these plain symptoms: his pulse will be full and strong, and somewhat quicker than it should; his complexion will be more florid; and his urine higher coloured. The veins also will be swelled, and his breathing will grow difficult.