Darwin published "On the Origin of Species" on November 24, 1859. The first printing was 1,250 copies, with some having been sent to America via ship; one of those was for Gray. Gray's copy arrived just before Christmas, and he read it between Christmas and New Year's. Since there was no international copyright law at the time, Gray worked to protect the book from publishing piracy. According to American law at the time, a copyright could only be secured by an American edition being published by an American citizen, and royalties were not required to be paid to the author. Gray arranged the first American edition of "On the Origin of Species" and was able to negotiate royalties on Darwin's behalf. Gray took a 5%royalty from the publisher, and Darwin was so grateful for Gray's efforts that he offered Gray some of his royalties. Darwin held Gray in high esteem: he dedicated his book "Forms of Flowers" (1877) to Gray, and he wrote in 1881, "there is hardly any one in the world whose approbation I value more highly than I do yours." Seeing the "unity we perceive in nature" and law in the universe, regarding all species he felt "that they not only "had" a Creator but "have" a Governor." Gray and Agassiz strongly disagreed; Agassiz was adamantly opposed to the idea of evolution, whereas Gray was a staunch supporter, believing in theistic evolution. As the debate raged over Darwin's theories, the rift between Gray and Agassiz grew deeper, and they were estranged by December 1863, when Gray was elected president of the American Academy of Arts and Sciences, which also marked Agassiz' increasing isolation within the scientific community. Gray showed little interest in scientific politics and resigned from the National Academy of Sciences in 1867. In late 1866 Agassiz apologized to Gray and the two were at least civil to one another again.