letter Sagredo lets fall the ominous words that he “was convinced _that as Galileo could not regain what he had lost_, he would take good care to hold fast what he had gained.”[65] Only a month after Galileo’s arrival at Florence he made a fresh discovery in astronomy which eventually contributed to confirm the Copernican theory, namely, the varying crescent form of the planet Venus. With this the important objection to the new system seemed to be removed, that Venus and Mercury did not exhibit the same phases of light as the moon, which must be the case if the earth moved, for they would vary with her position in the universe. Galileo communicated this appearance, which entailed conclusions so important, and which he therefore wished to investigate more thoroughly before making it known, to his friend and correspondent Julian de’ Medici at Prague, in an alphabetical enigma, as in the case of the singular appearance of Saturn. It was as follows: “Hæc immatura a me jam frustra leguntur o y.”[66] Having fully convinced himself by nearly three months’ observations that Venus and Mars exhibited phases similar to those of the moon, he made it known in two letters of 30th December[67] to Father Clavius, at Rome, and to his former distinguished pupil Benedetto Castelli, abbot of the congregation of Monte Cassino, in Brescia; and in a letter of 1st January, 1611, he sent the following solution of the anagram to Julian de’ Medici:— “Cynthiæ figuras æmulatur mater amorum.” In this letter he draws the important conclusions, first that none of the planets shine by their own light, and secondly “that necessarily Venus and Mercury revolve round the sun; a circumstance which was surmised of the other planets by Pythagoras, Copernicus, Kepler, and their followers, but which could not be proved by ocular demonstration, as it could now in the case of Venus and Mercury. Kepler and the other Copernicans may now be proud to have judged and philosophised correctly, and it may well excite disgust that they were regarded by the generality of men of book learning as having little understanding and as not much better than fools.”[68] At this time Galileo was also eagerly occupied with a phenomenon which was to be a further confirmation of the Copernican view of the universe, the spots on the sun. By attentively observing their motions on the sun’s disk he afterwards discovered the sun’s motion on its own axis, a fatal blow to the Ptolemaic system. Although to science it may be quite indifferent whether Galileo, or Fabricius, or the Jesuit father Scheiner first espied the spots on the sun (for they all lay claim to the discovery), for us it has its importance, because the bitter contention between Galileo and Scheiner on the subject materially contributed to set the stone rolling which, in its fall, was no less disastrous to the moral greatness of Galileo than to the erudition of Rome.