 de Candolle was the first to put forward the idea of " Nature 's war " , writing of plants being " at war one with another " with the meaning of different species fighting each other for space and resources . Charles Darwin studied de Candolle 's " natural system " of classification in 1826 when at the University of Edinburgh , and in the inception of Darwin 's theory in 1838 he considered " the warring of the species " , adding that it was even more strongly conveyed by Thomas Malthus , producing the pressures that Darwin later called natural selection . In 1839 de Candolle visited Britain and Darwin invited him to dinner , allowing the two scientists the opportunity to discuss the idea . 
