Pretty scientific, this, and not likely to be of interest outside the technical field of astronomers and scientists. He explores the solar system as understood today; he studies the necessary conditions for life; he indicates, by inference, how such approximate conditions could exist on other planets, but considers that the chances are weighted against such survivals. If they exist, they would undoubtedly be quite remote from our understanding. He makes no mention of the possibility of human life. Mars he defines as burned out; Venus as coming into her own.