Albert the Great, or Albertus Magnus, (1206-1280) was born in Swabia the son of a military nobleman. He was a Dominican priest who taught theology at Cologne and Paris and whose most distinguished student was Saint Thomas Aquinas. Albert was called Doctor universalis because of the breadth of his knowledge, which 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 truths which are naturally knowable and mysteries which can not be known without revelation. In this work he teaches that people can only reach God through Himself, that is, by leaving 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 of God through contemplation.