Whatever reader desires to have a thorough comprehension of an author's thoughts cannot take a better method than by putting himself into the circumstances and postures of life that the author was in upon every important passage as it flowed from his pen; for this will introduce a parity and strict correspondence of ideas between the reader and the author. Now, to assist the diligent reader in so delicate an affair, as far as brevity will permit, I have recollected that the shrewdest pieces of this treatise were conceived in bed in a garret; at other times (for a reason best known to myself) I thought fit to sharpen my invention with hunger; and in general, the whole work was begun, continued, and ended under a long course of physic and great want of money.