Books like Time and again by Clifford D. Simak

Time and Again envisions a future in which humanity has dispersed across the stars, relying on carefully engineered biological androids to support the frontier. Only certain star systems, such as 61 Cygni, remain inaccessible: after years of failed expeditions, a lone agent—Asher Sutton—was sent to investigate. Sutton’s ship was presumed destroyed, yet two decades later he reappears, inexplicably alive and bearing a revolutionary concept that could reshape the relationship between humans and their android creations. The novel follows Sutton’s struggle against forces that seek to suppress or manipulate his idea: loyalists of present‑day humanity who fear change, temporal agents from the future who attempt to preserve the status quo, and the androids who yearn for recognition and equality. Through his journey, readers explore the tensions of technological advancement, identity, and the ethical limits of humanity’s expansion across the cosmos.

First publish date: 1951