By the time I published my first book, I had ten books full of ideas in different copybooks, accumulated during the years of cowardliness.

Does the word "copybooks" here mean "a book containing models of handwriting for learners to imitate"? But it really makes no sense to me. Could anyone please help to interpret this?

Thanks!

By the time I published my first book, I had ten books full of ideas in different copybooks, accumulated during the years of cowardliness.

Does the word "copybooks" here mean "a book containing models of handwriting for learners to imitate"? But it really makes no sense to me. 

Could anyone please help to interpret this?