'You cannot prove that force (which physicists define as that which causes motion) would inevitably thus change its character under the above conditions. Again I maintain that matter, though it may in the future be eternal, was created by God with the most marvellous affinities, leading to complex definite compounds and with polarities leading to beautiful crystals, &c. &c. You cannot prove that matter would necessarily possess these attributes. Therefore you have no right to say that you have "demonstrated" that all natural laws necessarily follow from gravity, the persistence of force, and existence of matter. If you say that nebulous matter existed aboriginally and from eternity with all its present complex powers in a potential state, you seem to me to beg the whole question.' Please observe it is not I, but a theologian who has thus addressed you, but I could not answer him. In your present 'idiotic' state of mind, you will wish me at the devil for bothering you.[23] Yours very sincerely, CH. DARWIN. 18 Cornwall Terrace, Regent's Park: Sunday, Dec. 1878. My dear Mr. Darwin,--Many thanks for your portrait--not only from myself but also from the 'future Mrs. Romanes.' I am glad that you think well of the literary style of the book on Theism. As regards the remarks of the supposed theologian, I have no doubt that he is entitled to them. The only question is whether I have been successful in making out that _all_ natural cases must reasonably be supposed to follow from the conservation of energy. If so, as the transmutations of energy from heat to electricity &c. all take place in accordance with law, and as the phenomena of polarity in crystals &c. do the same, it follows that neither these nor any other class of phenomena afford any better evidence of Deity than do any other class of phenomena. Therefore, if all laws follow from the persistence of force, the question of Deity or no Deity would simply become the question as to whether force requires to be created or is self-existent. And if we say it is created, the fact of self-existence still requires to be met in the Creator.