Greetings,Sorry for so many questions, so you can answer only one if three are too burdensome.
1. Does this "As choolchildren" mean "When we are schoolchildren" or "As the title of schoolchildren"? When we are in school
2. What is the usage of "be" in "whether it be true"'? What's the difference with "whether it is true"? It is a subjunctive
3. I think this "could have believed" is not a conditional or presumption, but a present pefect meaning of "have been able to believe", right? "We are lef to wonder why/how come people believed what they were told..." is another wording that makes sense here, IMO.
ex)As schoolchildren, we learn that different weights fall at the same speed. This simple and readily tested observation, first published by Galileo, refuted Arisototle, who claimed that heavy things fall faster. Galileo put in in Two New Sciences, "I greatly doubt that Aristotle ever tested by experiment whether it be true..." We are left to wonder how people could have believed what they were told for two millennia without ever checking...