This is a rather dated collection of science fiction tales from the 30's, 40's, and 50's, but still pretty good. "Helen O'Loy" is the oldest tale in the book, and is considered something of a classic, more for its assessment of human nature than for its science, a caveat which is typical of Del Rey overall, who is not by any means a "hard" science writer. Many of these stories wrestle with philosophical issues, often from a robotic or other non-human perspective. The end of the human race is another common theme. There are a number of tales that strike this reviewer as anti-religion, which some may find borderline offensive, although the turning-against-God yarn "For I Am a Jealous People" is probably the most memorable story in the collection.
The earlier stories are generally the more precise, and feature clear moral lessons: the work ethic of "The Coppersmith", the hope for the future evoked in "Into Thy Hands", the release from ignorance in "Superstition". Overall, not a bad collection. Only the plotless dog story, "The Keepers of the House" is a complete failure. Of course many of the ideas in these stories have since been used by other writers in better stories, and while this isn't Lester's fault, it does somewhat undercut this book for modern readers. A sound enough choice for fans of the speculative fiction of this era, but because it's so old-fashioned in style and approach, and because there aren't any stories that are just essential, three stars seems enough.
