Unprovided with original learning, unformed in the habits of thinking, unskilled in the arts of composition, I resolved to write a book.

Gibbon frames his decision to “write a book” as an act of audacity undertaken in conscious awareness of his deficiencies. The triad—lack of “original learning,” undeveloped “habits of thinking,” and no “arts of composition”—functions as a rhetorical self-indictment that heightens the drama of intellectual self-fashioning: a major work begins not from mastery but from resolve. Read this way, the line underscores a theme common in literary self-narration: the author’s later authority is made more impressive by emphasizing early inadequacy, and the craft of historical writing is presented as something acquired through disciplined effort rather than inherited genius.