112 ALEXANDER VON HUMBOLDT. 



which the luminous matter constituting the basis of noxious 

 gases exerts a powerful influence. He requests, however, with 

 the unassuming love of truth by which he was even then so 

 honourably characterised, that the facts educed might not be 

 confounded with the explanation he had offered concerning 

 them, and quotes the too often neglected words of Spinoza : 

 ' Videmus enim omnes rationes, quibus natura explicari solet, 

 modos esse tantummodo imaginandi, nee nullius rei naturam, 

 sed tantum imaginationis constitutionem indicare.' 



Humboldt thus alludes to his literary occupations in a letter 

 to Wattenbach, written shortly before he left Freiberg, and 

 dated February 18, 1792 : 



6 If the few letters which I find time to write now did not all 

 begin with excuses, I should willingly find some for you, my 

 dear Wattenbach. But I am heartily tired of making the 

 everlasting excuse of want of time. I am indeed quite dis- 

 tressed not to have sooner answered your kind and affectionate 

 letter of November 14, but if you only knew how I am situated 

 here, I am sure you and Hiilsenbeck and all my other friends 

 would excuse me. If you will bear in mind that during the 

 nine months that I have been here, I have travelled nearly 

 700 miles on foot and by carriage through Bohemia, Thuringia, 

 Mansfeld, &c. that I am daily in the mines from six till twelve 

 o'clock (nearly two hours are occupied in the transit, which in 

 the snow is very fatiguing) that as many as six lectures are 

 crowded into an afternoon you will then be in a condition 

 yourself to pronounce my sentence. I have never been so 

 much occupied in all my life. My health has suffered in 

 consequence, although I have not been laid up with any serious 

 illness. Nevertheless I am on the whole very happy. I follow 

 a profession which to be enjoyed must be followed passionately; 

 I have acquired an immense amount of information, and I never 

 worked with so much facility as I do now. 



' Everlastingly about myself ! You have been ill, poor fellow ! 

 I heard of it from Maclean. I was heartily sorry for you. 

 Illness in itself is no misfortune, but the monotony of the life 

 and the commiseration of others is insupportable. The death 

 of Pepin and Metzer of Embden will be a loss to the Academy. 

 Pray take occasion to mention wherever you go that Von 





