I beg you, therefore, my dear Davy, to write me a long letter when you are at leisure, informing me: Firstly, What books it will be well for me and Calvert to purchase. Secondly, Directions for a convenient little laboratory. Thirdly, To what amount apparatus would run in expense, and whether or no you would be so good as to superintend its making at Bristol. Fourthly, Give me your advice how to _begin_. And, fifthly, and lastly, and mostly, do send a _drop_ of hope to my parched tongue, that you will, if you can, come and visit me in the spring. Indeed, indeed, you ought to see this country, this beautiful country, and then the joy you would send into me!
The shape of this paper will convince you with what eagerness I began this letter; I really did not see that it was not a sheet.
I have been _thinking_ vigorously during my illness, so that I cannot say that my long, long wakeful nights have been all lost to me. The subject of my meditations has been the relations of thoughts to things; in the language of Hume, of ideas to impressions. I may be truly described in the words of Descartes: I have been "res cogitans, id est, dubitans, affirmans, negans, pauca intelligens, multa ignorans, volens, nolens, imaginans etiam, et sentiens." I please myself with believing that you will receive no small pleasure from the result of these broodings, although I expect in you (in some points) a determined opponent, but I say of my mind in this respect: "Manet imperterritus ille hostem magnanimum opperiens, et mole suâ stat." Every poor fellow has his proud hour sometimes, and this I suppose is mine.
I am better in every respect than I was, but am still _very feeble_. The weather has been woefully against me for the last fortnight, having rained here almost incessantly. I take quantities of bark, but the effect is (to express myself with the dignity of science) _x_ = 0000000, and I shall not gather strength, or that little suffusion of bloom which belongs to my healthy state, till I can walk out.
God bless you, my dear Davy! and your ever affectionate friend,
P. S. An electrical machine, and a number of little knickknacks connected with it, Mr. Calvert has.--_Write._