You need these as a carpenter needs an adze and a pointer.

They are tools, but the tools cannot teach you how to make use of them.

Understand?
Let us see: Suppose an adze were handed to a carpenter for him to square a beam with it.

It's not enough to have hands and an adze; it is also necessary for him to know how to strike the wood so as not to hit his foot instead.

To you the knowledge of reading and writing is given, and you must regulate your life with it.