DNA cannot self-replicate like a crystal (an idea tracing to Schrödinger's 1942 Dublin lectures): chemical base-pairing alone yields an error rate of about 1 in 10,000 base pairs, which across 3 billion base pairs would produce hundreds of thousands of errors per division; the living cell instead deploys a controlled army of cut-and-paste correction enzymes that lower the error rate to about 1 in 10 billion.