How, therefore, can reading the upaniShad-s make one enlightened?
This is not a valid analogy. It is true that you cannot learn swimming by just reading books on how to swim. This is because reading or hearing about swimming does not give you direct knowledge about swimming. But the upaniShad-s actually give direct knowledge on Atman, and this is clearly pointed out by Adi Shankara. I guess you are familiar with the story about the Swami and his disciples crossing a river. When arriving on the other shore, the Swami counted his disciples and it turned out that only nine persons had successfully crossed the river! He counted all his disciples over and over again, concluding: “There is one missing. We are only nine people, and it should be ten!” Then a stranger walked by. He overheard the conversation, and said to the Swami: “But there are actually ten persons. You have forgot to count yourself. You are that tenth person!”. From the uttering of these words, the Swami at once realized that he was the tenth person. Well, the words of the stranger gave th
