Sometimes Hahnemann diluted a substance 1-to-9 (called "D1").
In this case any dilution of D24 or greater would also not likely contain any molecules of the remedy.
First, he said that "like cures like" (Similia similibus curentur).
This meant that a substance that produces certain symptoms in a healthy person can be used to cure similar symptoms in a sick person.
They would eat various plant, animal, and mineral substances and carefully observe what symptoms occurred.