Meditation is a tier two technology available after unlocking Climbing. Once researched, it gives troops in mountains a defensive bonus, similar to Archery and Aquatism. Also, it unlocks the Pacifist task, which gives you the Altar of Peace as a reward for completing it. To complete the Pacifist task, you have to make no attacks for 5 turns. Retaliation does not count as an attack. Meditation leads to Philosophy.