You perform Yajna (sacrifice) when you dedicate your actions in a spirit of cooperative effort to a higher ideal represented by the gods. Through concerted effort, when your physical, verbal, and mental energies are focused on the higher, you are performing Tapas (austerity). Daana (charity) refers to the social obligation to share your possessions with those in need, without expecting anything in return. Although such rituals do not directly reveal the Self, they should be performed to purify your mind. A purified mind is an essential prerequisite for gaining Knowledge-of-the-Self, which is the direct cause of liberation.