This conception dominated philosophy for two-thousand years. It even ends in this pessimistic situation. In science fiction typically evil aliens invade and menace mankind. Here it is the other way around. True, the Venusians are five thousand years too late for mankind, but they promise hope.
Rational life goes on within the universe.
Besides these paralleling features there are some significant reverse motives which correlate remarkably with each other. The kind of people struck by deception in the two stories is different. In the Allegory of the Cave the betrayed persons are described no further, thus, the reader will take them as common people. Today and in the future this lack of awareness accompanies science. An ironical note is that the Venusians are reptiles, mere animals in the tree of life on Earth.