Thales the Greek saw this while travelling in Egypt and took it back to Greece.
Measure twelve equal sections along a string, placing a knot to mark each section. The ends of the string are secured together in the ground as is the knot which marks the third section in either direction. Of the remaining nine divisions, select either knot which divides them into four and five and plcae it so that the string is straight. This creates a 3 : 4 : 5 triangle. The angle between the 3 units and the 4 units is a right angle.
The ancient Egyptians created right angles this way, after the annual Nile floods washed out boundary markers. They may have leaned this from the Sumerians
The 3, 4, 5 triangle is of interest because it is the only right triangle in which the numbers are consecutive.
The same method could be used to create vertical lines. Isis the earth-mother (4) is horizontal, Osiris the father-god (3) is erect and Horus their son (5) extends between them and reunites them. The area of the Horus square (25) is the sum of the areas on the other two sides (9+16)
This string also gives us a measuring length of twelve units, which in the process is divided into three and nine and eventually gives seven and five.
The Priestly Benediction in the original Biblical Hebrew words follows the 3, 5, and 7 pattern, again in order to reach a climax. The Lord bless thee and keep thee refers to material blessings; the Lord cause His face to shine upon thee and favor thee refers to spiritual enlightenment, and the Lord turn His face to thee and grant thee peace refers to the ability to enjoy both material and spiritual blessings together, a blissful state described as peace.