Linguistics
Linguistics is the scientific study of language, and involves an analysis of language form, language meaning, and language in context. The earliest activities in the documentation and description of language have been attributed to the 6th century BC Indian grammarian Pāṇini, who wrote a formal description of the Sanskrit language in his Aṣṭādhyāyī.
Literature
Literature, most generically, is any body of written works. More restrictively, literature writing is considered to be an art form, or any single writing deemed to have artistic or intellectual value, often due to deploying language in ways that differ from ordinary usage.
Philology
Philology is the study of language in oral and written historical sources; it is a combination of literary criticism, history, and linguistics. Philology is more commonly defined as the study of literary texts as well as oral and written records, the establishment of their authenticity and their original form, and the determination of their meaning. A person who pursues this kind of study is known as a philologist.
Literature
It is right for you, young men, to enrich yourselves with the spoils of all pure literature; but he who would make a favorite of a bad book, simply because it contains a few beautiful passages, might as well caress the hand of an assassin because of the jewelry which sparkles on his fingers.
Joseph Parker, p. 386.
Linguistics
Small Latin, and less Greek.
Ben Jonson, To the Memory of Shakespeare.
Literature
* * * A man of the world amongst men of letters, a man of letters amongst men of the world.
Thomas Babington Macaulay, 1st Baron Macaulay, On Sir William Temple.