E.R.B. wrote hundreds of books and I once owned about 130. Having trashed my library when called upon to move back in 2010, I am now glad to be able to revisit books read in my youth via an audio book.
His series on The Earth’s Core, a fantasy written in 1914, was especially appealing to me because of the over whelming savagery of the reptilian villains and their ape man slaves. I recall owning seven volumes published over an impressive span. The two best volumes I recall being Tarzan at the Earth’s Core, in which the center of the earth is accessed through an arctic airway in a zeppelin, and Seven Worlds to Conquer, also titled Back to the Stone Age. The 1960s -70s artwork by Frazetta, featuring phenomenally sexy cave girls, went a long way towards selling the $1.50-$1.95 paperbacks.
The second volume, Pellucidar, was okay. I prefer this, the first volume. E.R.B. is up to his tried and true recipe for immersing the civilized reader in a savage setting, by following an educated and cultured man into it—a man who just happens to have been a football player, baseball player, and boxer of exceptional strength. In E.R.B. stories wimps need not apply for the leading role.
The theme in the Pellucidar novels is that an exceptional modern man, willing or forced to examine his inner savage, might be able to harness his baser nature to his evolved ethos in order to positively affect the most savage world. At the Earth’s Core is an extension of the Tarzan concept of stressed human devolution back into a purer, more vibrant, state, as seen through the eyes of a hero not half as savage as Tarzan, but savage enough to survive in primitive conditions.
The nature of life within a sphere, is well wrought by the author, and might have inspired Gene Wolfe’s Litany of the Long Sun, about a hollowed out asteroid launched as a generation ship. In Pellucidar even the rain is deadly, for it falls in such heavy sheets that animals fear to be caught out in the open.
The villainous twist in the Pellucidar series is a little heavy for Burroughs, with the reptilian Mahars raising humans as livestock and devouring them in gruesome detail. The Mahars represent modern mass society, where the females [representing emasculation] rule, through hypnosis, providing an allegory for the insidious nature of modern ideologies disseminated by electronic means. The mesmerist Mahars are fitting as the queens of a Garden of Eden clothed in the scales of the reptile.