alpha and omega

The beginning and the end; the entirety of something. (Alpha and omega are the first and last letters of the Greek alphabet.) In order to do well on the exam, you need to know the alpha and omega of the textbook.

both the beginning and the end; the essentials, from the beginning to the end; everything, from the beginning to the end. He was forced to learn the alpha and omega of corporate law in order to even talk to the lawyers. He loved her deeply. She was his alpha and omega.

The beginning and the end, the first and the last, as in She had to master the alpha and omega of the new computer program before she could even begin . This idiom and its meaning, based on the first and last letters of the Greek alphabet, appears in the New Testament (Revelation 1:8): "I am Alpha and Omega, the beginning and the ending, saith the Lord," where it is repeated three more times.