What is the connection between writing well and reading thoroughly?

In order to read thoroughly, one must have a good command (knowledge) of the language.

When someone writes well, they understand that each word has an impact on the reader. That impact must be calculated, writing cannot be just a collection of words or written in a conversational style.

Therefore, if one has a good command of language and how to use it, situations can be developed in their writing when attact and hold people's attention.

Reference: Old Swabbie