Spit and Image of the Old Man

What is the most interesting idiomatic expression in American English and what is the history/story behind it?

He’s the spit and image of his father. See 'Spitting image' - the meaning and origin of this phrase. “26 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. 27 So God created man in his own image, in the image of God created he him; male and female created he them” (Genesis 1:26–27). “And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul” (Genesis 2:7 KJV).

Image from The Book of Genesis Illustrated by Robert Crumb (2009)

Note that it takes two requirements to create a man in God’s image: (1) the dust of the ground, and (2) the breath of life. There is always an influx of God’s energy - whether it be breath or some other emanation, for example, saliva or spit. In this connection, it’s worthwhile to look at John 9:6–7.

“When he had thus spoken, he spat on the ground, and made clay of the spittle, and he anointed the eyes of the blind man with the clay, And said unto him, Go, wash in the pool of Siloam, (which is by interpretation, Sent.) He went his way therefore, and washed, and came seeing.”

The occasion is being born again in the light of the Lord. Just as breath imbued the dust of the earth with spirit, so does the saliva of Jesus fill the man with the Holy Spirit.

Thus do spirit and image, or “spit and image,” make humankind the very image of God.