Socrates comes from a period, the tail end of that period, where all learning was oral. Writing was "new". He observed, which is provable and true, that learning from a written word perspective is a weaker form of learning than from an oral perspective. From the simple fact that when information is delivered orally, questions can be asked, it is a 2-way communication. Not so with writing. With writing, the student must follow their reading with additional oral use and trial uses of the information, or it is lost completely. While that same information initially gained in understanding via oral lessons can often be put to use immediately, the oral instructional path is more complete, it allows questions and answers during the learning process. While a written lesson requires human interactions to supplement that learning for it to hold.