After Socrates and the beginning of classical political philosophy, it is valuable to read old books because there is an inheritance and a community of the greatest minds and thoughts for us to be elevated by. There is nothing else like that experience truly available to us, not that I have ever found.
After Hobbes and the Industrial Revolution, it is valuable to read old books because we have been pulled out of the sort of political and technological existence that aligns closely to humanity’s instinctual patterns, and so there is a new barrier on top of all the old ones to prevent us from ascending to the realization of our moral and intellectual potential.
After Rousseau and the French Revolution, and after Marx and the Russian Revolution, it is valuable to read old books because human nature has lost its moorings and it bearing, and so to have something by which to orient ourselves becomes necessary and beneficial as never before.
After Nietzsche and the palingenetic fascisms, it is especially valuable to read old books. Their testimony can rescue us from the common modern mistake of thinking that in order to reject modernity’s vices, we must also reject its virtues. It is possible to distinguish baby from bathwater, and to become strong, for example, without needing to become cruel.