The name "Onement" is an archaic derivation of the word "atonement", that means "the condition of being made into one".
This painting is considered the breakthrough of Newman's work and the first complete incarnation of what the artist will later call a "zip".
The canvas is almost completely coloured in a dark brown tonality, but in the centre, there is a straight yellow line, unevenly painted, that vertically crosses the entire artwork.
This thin line is a "zip", a vertical band of colour, and is a motif that frequently comes back in Newman's paintings. A zip does not divide the canvas, but instead, it unifies the two sides of it. This thin yellow line carries a sense of mystery and tries to draw the audience to experience the painting both emotionally and physically.
"Onement I" is just the first painting of a big series of artworks, all inspired by the same spatial concepts. Newman painted a series of six canvases with the same theme (Onement I, II, III, IV, V and VI) and many others with different variations of the number and the orientation of the "zips", including The Wild (1950), Black Fire I (1961), Voice of Fire (1967), By Twos (1949) and Dionysius (1949). The last one features a green and blue canvas with two horizontal lines.
The spatial configuration of "Onement I" can be frequently recognised in other Newman's paintings and also in his sculpture "Broken Obelisk". This monument, also called the "Black Needle", is constituted by a combination of a pyramid and an inverted obelisk, one sitting on the top of the other.
Formally speaking the sculpture rephrases in a three-dimensional space the concept of the thin vertical "zip" travelling from the ground to the sky across the artwork.