Charles Darwin, writing in his notebook in 1838, asserted that man thinks of himself as a masterpiece produced by a deity, but that he thought it "truer to consider him created from animals." In his 1871 book "The Descent of Man", Darwin argued that:There is no fundamental difference between man and the higher mammals in their mental faculties ... he difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind. We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, etc., of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals.Henry S. Salt in his 1892 book "Animals' Rights," argued that for humans to do justice to other animals, that they must look beyond the conception of a "great gulf" between them, claiming instead that we should recognize the "common bond of humanity that unites all living beings in one universal brotherhood".