The relation of the notes of the musical scale to numbers, whereby harmony results from vibrations in equal times, and discord from the reverse, led Pythagoras to apply the word “harmony” to the visible creation, meaning by it the just adaptation of parts to each other. This is the idea which Dryden expresses in the beginning of his “Song for St. Cecilia’s Day”: “From harmony, from heavenly harmony This everlasting frame began; From harmony to harmony Through all the compass of the notes it ran, The Diapason closing full in Man.” In the centre of the universe (he taught) there was a central fire, the principle of life. The central fire was surrounded by the earth, the moon, the sun, and the five planets. The distances of the various heavenly bodies from one another were conceived to correspond to the proportions of the musical scale. The heavenly bodies, with the gods who inhabited them, were supposed to perform a choral dance round the central fire, “not without song.” It is this doctrine which Shakspeare alludes to when he makes Lorenzo teach astronomy to Jessica in this fashion: “Look, Jessica, see how the floor of heaven Is thick inlaid with patines of bright gold! There’s not the smallest orb that thou behold’st But in his motion like an angel sings, Still quiring to the young-eyed cherubim; Such harmony is in immortal souls! But whilst this muddy vesture of decay Doth grossly close it in we cannot hear it.” —_Merchant of Venice._ The spheres were conceived to be crystalline or glassy fabrics arranged over one another like a nest of bowls reversed. In the substance of each sphere one or more of the heavenly bodies was supposed to be fixed, so as to move with it. As the spheres are transparent we look through them and see the heavenly bodies which they contain and carry round with them. But as these spheres cannot move on one another without friction, a sound is thereby produced which is of exquisite harmony, too fine for mortal ears to recognize. Milton, in his “Hymn on the Nativity,” thus alludes to the music of the spheres: “Ring out, ye crystal spheres! Once bless our human ears (If ye have power to charm our senses so); And let your silver chime Move in melodious time, And let the base of Heaven’s deep organ blow; And with your ninefold harmony Make up full concert with the angelic symphony.” Pythagoras is said to have invented the lyre. Our own poet Longfellow, in “Verses to a Child,” thus relates the story: “As great Pythagoras of yore, Standing beside the blacksmith’s door, And hearing the hammers as they smote The anvils with a different note, Stole from the varying tones that hung Vibrant on every iron tongue, The secret of the sounding wire, And formed the seven-chorded lyre.” See also the same poet’s “Occultation of Orion”— “The Samian’s great Æolian lyre.”