Sixty years ago this month, scientist Francis Crick wrote a letter to his 12-year-old son saying he and a colleague had discovered something "very beautiful" - the structure of DNA.
Now, the note and its hand-drawn diagrams are being auctioned off in New York.
Christie's estimates the letter could fetch $1 million or more at the April 10 sale.
Crick's letter describes to his son how he and James Watson found the copying mechanism "by which life comes from life." It includes a simple sketch of DNA's double helix structure which Crick concedes he can't draw very well.
Now-72-year-old Michael Crick said Saturday he immediately understood his father had made a breakthrough.
Half the auction's proceeds will benefit the Salk Institute for Biological Studies in La Jolla, Calif.