Why was Isaac Newton sent back to grammar school instead of becoming a farmer?

After his mother was widowed a second time, she initially intended for Isaac Newton to manage her property and become a farmer. However, it quickly became apparent that this would be a disaster for both the estate and Newton himself. He proved unable to focus on rural responsibilities; for instance, when he was tasked with watching the cattle, he would instead curl up under a tree to read a book.1

Recognizing that this was a mistake, his family sent him back to the grammar school in Grantham, where he had previously studied, to prepare for university.1