IDEAS TO BE PUBLISHED 373 



Another letter to Harvey (February 3, 1857) strongly 

 repeats this appeal against the natural depreciation of his 

 own familiar store of knowledge, and insists on man's duty 

 of giving his formed ideas to the world. 



I am quite prepared for what you say of your work, it 

 was always my case on first venturing, nevertheless you 

 have done a great deal already and will soon fall into the 

 way of it. A few steady weeks at Systematic Botany in 

 the Herb, wondrously renovates and reinvigorates one I 

 find, and when weary of desultory head work, I find the 

 Herb, a great rehef. 



As to your publications I would urge you to think now 

 of putting together some of your ideas and facts on wider 

 branches than purely descriptive. I think that this becomes 

 a duty after a certain time of life with those who keep 

 such subjects before them — too much of our dear bought 

 experience dies with us, and the pursuit of careful descriptive 

 Botany rather renders us too timid about striking out into 

 generalities that are the product of years of insensibly gained 

 ideas. I express myself abominably and write as I think, 

 but I am myself urged on all hands to treat some branches 

 of Botany in a larger manner, and as soon as I have completed 

 my rough hsts of Indian and of Australian plants I intend 

 to make them the data on which to estabHsh some attempts 

 to estimate accurately the relations of numbers of genera 

 and species in given areas with chmate and elevation, the 

 relations numerical of genera to orders, of number of species 

 in globe, etc., etc., in short to bring to book upon absolute 

 data (tolerable as far as they go) certain principles now 

 vaguely enunciated on no fixed data at all. This you could 

 do for Southern Algae and connect their migration with 

 ocean currents and temp, of Ocean, not in detail, nor upon 

 exact data, but upon fair data, and be they good or bad you 

 are the only one capable of doing it, and it will take any other 

 man many years to come up to your capability and oppor- 

 tunity. Heaven knows I dread my subject and feel enough 

 my own incompetence, but the work wants doing, nobody 

 else has the opportunity, and it is in my position of life as 

 clearly my duty as any moral obUgation can well be. Others 

 can and will work up species, and I have no right to withhold 



VOL. I 2 b 



