The book aroused international interest, with less controversy than had greeted the popular and less scientific "Vestiges of the Natural History of Creation". Though Darwin's illness kept him away from the public debates, he eagerly scrutinised the scientific response, commenting on press cuttings, reviews, articles, satires and caricatures, and corresponded on it with colleagues worldwide. The book did not explicitly discuss human origins, but included a number of hints about the animal ancestry of humans from which the inference could be made.</ref> The first review asked, "If a monkey has become a man–what may not a man become?" and said it should be left to theologians as it was too dangerous for ordinary readers.</ref> Amongst early favourable responses, Huxley's reviews swiped at Richard Owen, leader of the scientific establishment Huxley was trying to overthrow. In April, Owen's review attacked Darwin's friends and condescendingly dismissed his ideas, angering Darwin, but Owen and others began to promote ideas of supernaturally guided evolution. Patrick Matthew drew attention to his 1831 book which had a brief appendix suggesting a concept of natural selection leading to new species, but he had not developed the idea.