Red ochre is iron. The same element that makes blood red — haematite, iron oxide, Fe₂O₃ — is what gives the oldest pigment its color. The iron in the ochre and the iron in the blood of the person who ground it and applied it are the same element, forged in the same stellar processes, distributed through the solar system by the same ancient impacts and accretions.
This is not a metaphor. It is chemistry. The person at Blombos who ground ochre 75,000 years ago was using iron to leave a mark on stone. The iron in their blood was enabling the muscular action required. The iron in the earth had been there since before the planet cooled. There is a continuity here that goes back to the formation of the solar system, approximately 4.6 billion years ago, when the iron was synthesized in the cores of stars that preceded our sun and exploded to seed the cloud from which the solar system formed.
The ochre on stone paper in the studio carries this history in its chemistry. I try not to lose sight of it.