The first occasion upon which this device was used appears to be in a book so rare that no copy of it can be found, either in the British Museum or the Bodleian Library. Unfortunately, in the copy belonging to the writer, the title-page and the two first pages are missing. The work is called "Hebraicum Alphabethum Jo. Bovlaese." It is a Hebrew Grammar, with proof-sheets added. It is interleaved with sheets of English-made paper, containing Bacon's handwriting. Bound up with it is another Hebrew Grammar, similarly interleaved, called "Sive compendium, quintacunque Ratione fieri potuit amplessimum, Totius linguæ," published in Paris in 1566. The book ends with the sentence: "Ex collegio Montis--Acuti 20 Decembris 1576"; then follow two pages in Hebrew, with the Latin translation over it, headed "Decem Præcepta decalogi Exod." Over this is the design containing the light A and the dark A, and the squirrel and rabbits. (Figure IX.) One thing is certain, that the copy now referred to was in the possession of Bacon, and that the interleaved sheets of paper contain his handwriting, in which have been added page by page the equivalents of the Hebrew in Greek, Chaldæic, Syriac and Arabic. In 1577 Christophor Plantin published an edition of Andrea Alciat's "Emblemata." On page 104 is Emblem No. 45, "In dies meliora." This has been re-designed for the 1577 edition. It contains at the back the pillars of Hercules, with a scroll around bearing the motto: "Plus oltre." These pillars stand on some arches, immediately in front of which is a mound or pyramid, two sides of which are seen. On one is to be found the light A and on the other the dark A. The design was appropriated by Whitney, and appears on page 53 in the 1586 edition of his Emblems. From this time forth, A A devices are to be found in numbers of books published in England, and on some published on the Continent. Amongst the former are the first editions of "Venus and Adonis," "Lucrece," the "Sonnets," the quarto editions of Shakespeare's plays, the folio edition (1623) of his works, and the first quarto and octavo editions (1612) of the Authorised Version of the Bible. There are fourteen distinct designs, in all of which, varying widely in other respects, the light A and the dark A constitute the outstanding figure. The use of the two letters so shaded must have had a special significance. In nearly every case it will be observed that the letter A is so drawn as to make the letter C on the inside. Was its significance of general knowledge amongst printers and readers, or was it an earmarking device used by one person, or by a Society? A possible interpretation of the use of the light and dark shading, is that the book in which it is used contains more than is revealed; that is to say, the overt and the concealed.