The incomparable, great Atisha pointed out that Buddha Shakyamuni taught 84,000 different sets of Dharma teachings, and so it's actually quite difficult to learn them all in this brief lifetime... So, one should take the very essence of these Dharma teachings. To take the essence of milk, one churns it until one comes away with butter. Similarly, if we churn the Dharma -- all that knowledge of what needs to be learned and practiced -- in order to take the essence of what we need to do in this brief life, the indispensable essence that we come up with, which we absolutely must practice in order to progress toward the final goal of full enlightenment, is the precious mind of bodhichitta!

-- Ribur Rinpoche