LETTER TO MRS. HOLBROOK. 499 



races themselves. It has occurred to me that 

 as a preliminary inquiry we ought to con- 

 sider the propriety of applying to man the 

 same rules as to animals, examining the limits 

 within which they obtain, and paying due at- 

 tention to all circumstances bearing upon the 

 differences observed among men, from what- 

 ever quarter in the study of nature they may 

 be gathered. What do the monkeys say to 

 this ? or, rather, what have they to tell in 

 reference to it? There are among them as 

 great, and, indeed, even greater, differences 

 than among men, for they are acknowledged 

 to constitute different genera, and are referred 

 to many, indeed to more than a hundred, 

 species ; but they are the nearest approach to 

 the human family, and we may at least derive 

 some hints from them. How much mixture 

 there is among these species, if any, is not at 

 all ascertained ; indeed, we have not the least 

 information respecting their intercourse ; but 

 one point is certain, zoologists agree as lit- 

 tle among themselves respecting the limits of 

 these species as they do respecting the affini- 

 ties of the races of men. What some consider 

 as distinct species, others consider as mere va- 

 rieties, and these varieties or species differ in 

 particulars neither more constant nor more 



