The Sentinel by Arthur C Clarke and 2001: A Space Odyssey

The theme of "The Sentinel" was the belief that the evolution of an intelligent species would eventually make them something close to gods.
The story deals with the discovery of an artifact on Earth's Moon left behind eons ago by ancient aliens. The object is made of a polished mineral and rectangular in shape, and is surrounded by a spherical force field. The artifact has transmitted signals into deep space, but it ceases to transmit when the astronauts who discover it breach the force field. The narrator imagines that this "sentinel" was left on the moon as a "warning beacon" for the possible intelligent and space faring life that might develop on Earth.
This quotation illustrates the idea, and its consequences:
"It was only a matter of time before we found the pyramid and forced it open. Now its signals have ceased, and those whose duty it is will be turning their minds upon Earth. Perhaps they wish to help our infant civilization. But they must be very, very old, and the old are often insanely jealous of the young."
In the movie 2001: A Space Odyssey, the operation of the sentinel is reversed. It is the energy of the sun, falling for the first time on the uncovered artifact that triggers the signal that creatures from the Earth had taken the first step into space.