A fun fact that please excuse me if off-topic: Mao Zedong was a librarian before he started the Bolshevik Revolution in China, and then he changed all of China. So it's often said in China that it's really dangerous to upset a librarian.

Wasn't Lao Tzu a librarian as well?

Is it known which kind of books he read?

My understanding is that Mao was a rural peasant from the distant Countryside who was looked down on and marked by his more (self declared) socialist Coastal betters along China's Coast who were contesting with the kmt and later Japanese invasion. The idea that Mao invented the communist or socialist revolution in China is laughable because that revolution had been ongoing prior to Mao's entrance into it. My understanding is that Mao was the guy that stood up and said look, the peasants in the Hinterlands are an Unstoppable Army that is going to come flooding from distant and Central China on to the coast and push all opposition aside and so Mao was basically saying that that the Communists should be attempting to position themselves as favorably as possible in relation to the rising peasant tide of discontent in China. If anything the concern is that if you say anything that the modern Chinese Communist party does not like or agree with they will disappear you to all the corners of the Earth. It is probably only in Taiwan that you could speak openly and honestly about the nature of modern Chinese history from let's say 1900 to the current day. They probably have a better accounting of what was actually going on, and that will soon be deleted by the now dominant Communist Party of China. You can see how they have treated their assimilation of Hong Kong, and Macau before them to imagine what awaits Taiwan.