The concept of the symbol was vitally important to Coleridge throughout his career as a poet, critic and professional man of letters. Although his articulation of this concept varied in emphasis at different moments of his career, the underlying concept of symbol remained important as a fundamental principle throughout his intellectual development. During the last two centuries, the concept of the symbol has become one of Coleridge's most influential contributions to the discourse of literary criticism.

One persistent area of concern throughout Coleridge’s career is the question of the relation between language and thought. Coleridge formulates this question as follows: ‘Is Logic the Essence of Thinking? in other words – Is thinking impossible without arbitrary signs? & – how far is the word “arbitrary” a misnomer? Are not words &c parts & germinations of the Plant? And what is the Law of their Growth?’ (CLi, 625). Coleridge is here pondering whether the arbitrary signs that, according to such contemporary linguists as John Horne Tooke, determine thought can in some sense be described as ‘natural’. This question is a central one for Coleridge; it recurs at several crucial moments in his intellectual career. The concept of symbol, as it evolved in his mature philosophy of language, was in large part an effort to overcome the arbitrariness of the linguistic sign, and to demonstrate that at least in the realm of poetry, language could become the actual embodiment of thought.