Full Idea
When a man is born, the Stoics say, he has the commanding-part of his soul like a sheet of paper reading for writing upon; on this he inscribes each one of his conceptions.
Gist of Idea
At birth the soul is a blank sheet ready to be written on
Source
report of Stoic school (fragments/reports [c.200 BCE]) by Aetius - fragments/reports 4.11
Book Reference
'The Hellenistic Philosophers:Vol.1 translations', ed/tr. Long,A. /Sedley,D. [CUP 1987], p.238
A Reaction
This appears to be the origin of the concept of the 'tabula rasa', which resurfaces in empirical thought, in Locke and elsewhere. Notice that 'he' inscribes on the paper, rather than raw experience doing the job. The natural light of reason can do it.