But to give you a just and rational Idea of its Power of moving and actuating upon the Body, let us consider the whole human System as a Compound of Tubes and Glands, or to use a more rustick Phrase, a Bundle of Pipes and Strainers, fitted to one another after so wonderful a Manner as to make a proper Engine for the Soul to work with. This Description does not only comprehend the Bowels, Bones, Tendons, Veins, Nerves, and Arteries, but every Muscle and every Ligature, which is a Composition of Fibres, that are so many imperceptable Tubes or Pipes interwoven on all Sides with invisible Glands and Strainers. This general Idea of a human Body, without considering it in the Niceties of Anatomy; let us see how absolutely necessary Labour is for the right Preservation of it. There must be frequent Motions and Agitations to mix, digest, and separate the Juices contained in it, as well as to clear and cleanse that Infinitude of Pipes and Strainers of which it is composed, and to give their solid Parts a more firm and lasting Tone; Exercise ferments the Humours, casts them into their proper Channels, throws off Redundancies, and helps Nature in those secret Distributions, without which the Body cannot subsist in Vigour, nor act with Chearfulness. I might here mention the Effects which this has upon the Soul, upon all the Faculties of the Mind, by keeping the Understanding clear, the Imagination untroubled, and refining those Spirits that are necessary for the proper Execution of our intellectual Faculties, during the present Laws of Union between Soul and Body. It is a Neglect in this Particular, that we must ascribe the Spleen, which is so frequent in Men of studious and sedentary Tempers; as well as the Vapours, to which those of the other Sex are so often subject. Had not Exercise been absolutely necessary for our Well-being, Nature would not have made the Body so proper for it, by giving such an Activity to the Limbs, and such a Pliancy to every Part, as necessarily produce those Compressions, Extensions, Contortions, Dilatations, and all other Kind of Motions that are necessary for the Preservation of such a System of Tubes and Glands as has been before mentioned. And that we might not want Inducements to engage us in such an Exercise of the Body as is proper for its Welfare, it is so ordered, that nothing valuable can be procur'd without it. Not to mention Riches and Honour, even Food and Raiment are not to be come at without the Toil of the Hands, and Sweat of the Brows.