symbologyBibleNumbers

As Bullinger points out, "three" is the first of four perfect
numbers in Scripture.
3 "Three" denotes divine perfection.
7 "Seven" (as in seven days in the week) denotes
spiritual perfection.
10 "Ten" denotes ordinal perfection (Ten
Commandments, the tithe is a "tenth", Noah was
the "tenth" generation from Adam).
12 And "twelve" (as in twelve sons of Jacob, twelve
apostles) denotes governmental
perfection.
Hence, the number three points to
that which is real, substantial, perfect, complete,
essential, and Divine.
There were three Patriarchs -- Abraham, Isaac, and
Jacob.