Bacon's essay is a diatribe on studying, the ways and purposes, and categories. As mentioned in reply #2, the purposes one might have for reading/studying are 1)delight 2) ornament and 3) ability. The books you choose to read for "delight" are to be "tasted"--much like a delectable dessert after an amazing meal. You might take one or two bites, but you're full of other stuff, and there's no room for the entire cake, or whatever.
The books that you keep for ornament (maybe you haven't read it in full or just like the prestige it brings you for having it on the coffee table) are to be "swallowed"--like Rambo and his raw eggs (or someone taking nasty tasting medicine), you don't really get anything from it as far as taste, or in this case, knowledge. The food goes right by the taste buds so quickly that you barely even know it's there.
The third purpose, is ability--this is where you really want to "chew and digest"--ponder the information the books contain, chew it, mull it over, question and dscuss, let it sink in and then digest it for further benefit to your body, mind and soul.
Of Studies discusses the benefits of studying. Its purpose is to persuade us to study as well as to instruct us on how to study if we are to make the best of what we read. He does this by using many rhetorical devices and substantiations to prove his arguments.
Of Studies, one of Bacon's earliest essays, is a brief but compact piece of counsel on the subject of the uses & abuses of studies, the choice of books, and the curative/remedial aspects of different disciplines. Bacon effectively combines practical utility with his sense of wisdom to offer a prescriptive view of studies.
First, Bacon refers to three major purposes of studying books: delight, ornament, & ability. The purposes are in an ascending pattern of priority. He also wants the knowledge derived from books to be verified by actual experiences.
Secondly, Bacon divides all books into three categories: 'books to be tasted','books to be swallowed', 'books to be chewed and digested'. The first category contains those books which may be necessary, but not worth-reading in full. The second class of books refers to books unpleasant, but shall have to be somehow read in full. The third category contains the real good books which must be read with attention & insight.
Finally, Bacon argues that just as various physical exercises can cure physical maladies, mental defects/deficits can be cured by various branches of studies.