Square symbol for Finnegans Wake

As it can be seen at the Introduction of Finnegans Wake from Oxford Series:

3.The title, . pp. 139-40

The third question in the quiz concerns the title of the book, something Joyce, a riddler like Shem and Stephen Dedalus, dept secret from everyone except his wife Nora. While Joyce held on to the secret, the work appeared under the temporary title 'Work in Progress' He teased Harriet Shaw Weaver this munificent patroness, about the real title to keep up her flagging interest in the book - an only partially successful ruse. The square symbol for the book (or for the title that stands for it) can stand for a house, a pub, an asylum, a hospital, a toilet, a phone -box, even a coffin - any container, frequently an institutional edifice. Like this square the book has four 'sides', though they're far from equal: 'I am making an engine with only one wheel... The wheel is perfect square' (LI 251). The title itself, Finnegans Wake, finally guessed in August 1938 by Eugene Jolas, the editor of the magazine Transition in which instalments of 'Work in Progress' had been appearing, is 'nothing Grand nothing Splendid'(140.3-4), an indication of a kind of lowliness that is consistent with the song 'Finegan's Wake' from which the title is taken. This was an Irish-American comic song from the 1860s about a builder who is thought to have died but whose corpse, lying still at his own wake, nonetheless stirs when whiskey is spilled and splashes on his face and who then calls out for more. Joyce transformed the title of the song by removing the apostrophe. the title then becomes a sentence in which Finnegans (the plural noun) Wake (present tense verb).

and

Ireland on Stage: Beckett and After

... Jung views the square in this dream as having arisen from a circle that the patient had seen in a former dream, interpreting the square in terms of the Quadrature, or squaring, of the circle, and thus as denoting an alchemical mandala. That is, the Quadrature of the circle symbolises alchemy, it affords a way from chaos to unity, a method by which the four elements - earth, air, fire and water - represented by the square, can be brought into unity in the shape of the circle.
Elias Lévi, who greatly influenced the occult thought of Yeats and Joyce, defines the Quadrature of the circle in similar terms:

So unity, complete in the fruitfulness of the triad, forms therewith the square and produces a circle equal to itself, and this is the Quadrature of the circle, the circular movement of four equal angles around the same point.