Our reconstruction of Symonds's library is based on several kinds of sources, each of which requires specific criteria of interpretation and selection.
- Surviving copies of books bearing Symonds's bookplate, bookstamp, or other ownership marks. We aim to include all such books known to us. Most of these are held in public libraries and private collections, but some we have recorded from the advertisements (usually online) of present-day booksellers.
- Books indicated as coming from Symonds's library by auction catalogues and other printed bookseller catalogues and lists. We also aim to include all of these. Note that this produces the occasional anomaly of a book published after Symonds's death. These presumably are books added to the library by Symonds's surviving family members or sent to him by authors or others in ignorance of his death.
- Books that Symonds in surviving texts (including his Memoirs, correspondence, and published works) explicitly indicates or strongly suggests he possessed. Often this requires case-by-case assessment. For example, books Symonds describes consulting at home in Clifton or after his move to Davos are assumed to be part of his personal collection rather than books consulted in public or private libraries. (Here and elsewhere, we are not excluding books acquired by John Addington Symonds, Sr., since these would have passed to Symonds upon his father's death.) During the periods when he had ready access to the libraries of Harrow, Oxford, or London, we aim to be more cautious, though some books he persistently cites may be included.
- Books that can be identified in surviving photographs of Symonds in his study.
- Subscription lists and other miscellaneous evidence.