Albert the Great was born in Swabia, the son of a military nobleman. He was a Dominican priest who taught theology in Cologne and Paris. His most distinguished student was Saint Thomas Aquinas. Albert was called "Doctor universalis" because his breadth of knowledge spanned not only philosophy and theology but all the natural sciences. He was a dedicated student of nature, and although he argued that the physical world can only be known reliably through observation and comparison, Albert distinguished between thruths, which are naturally knowable, and mysteries, which cannot be known without revelation. People can only reach God through Himself - that is, by leaving behind the entanglements of earthly things and contemplating Him exclusively. The image and reality of God's incarnation in Jesus gives human beings the opportunity to attain a more perfect knowledge God through contemplation. Albert refers to the teaching of St. Peter, "Cast all your anxiety on him, because he cares for you."