1. Aleph, first letter of the Hebrew Alphabet.
It symbolizes the beginning of something when used as a concept instead of just a letter and part of other words. For lack of specific words for numbers, the Hebrews use the alphabet as numbers, so this is also the number “1”. This symbol is also used as a manuscript notation for a specific (very early) Greek manuscript, an Alexandrian manuscript found in a monastery in Mount Sinai.
2. A and O (alpha and omega), first and last.
These two letters are the beginning and ending letters of the Greek alphabet, and likewise, represent symbolically the beginning and end of something. God uses this pair as a description of His own eternity, i.e. God is before the beginning, and is after the ending if that is possible. (See Rev 1:8; 21:6, comparing with Isa 41:4; 44:6; 48:12). This divine attribute is described with the term “aseity”, which defines what God is. God’s aseity is God’s “aloftness” from Creation, the world, time, etc. While created things have a beginning and an end, and they have what is considered a limited duration, God in his being is without their restrictions. God has always existed, and this is what makes God what he is, God. Only God has this element, and it is technically referred to as “Aseity.”
The fact that God (Jehovah) uses this term to describe his eternity and aseity, which sets God apart from all creation and the coordinating fact that Jesus is also identified with this proves the deity of Jesus In Rev 1:8, 17, the Lamb of God (obviously referring to Jesus) is attributed with having the name “Alpha and Omega”, which gives Jesus the attribute of aseity. So Jesus is set apart from the world in this exclusively divine quality.
The first letter of the alphabet represents the beginning of things. Jesus is the beginning of all things (and the end or summation of all things).