Our Sages state that G-d created the world because he desired "a dwelling in the material realm." As a rule, a person fulfills his or her purpose in life not by secluding himself in a room and praying and learning all day, but by going out into the world and laboring to transform it into a holy and G-dly place. But to properly achieve this goal, our involvement with the material should be preceded by a period of total immersion in the spiritual. So it was in the history of our people: Israel's entry into the Land was preceded by 40 years in the desert. So it is on the individual level: the first years of life are marked by freedom from material cares, so as to fully devote oneself to learning. And so it is on the daily level: each day begins with time set aside for prayer and Torah study.

From an address by the Rebbe, Spring 1962 (free translation)