THE PLA.NETS. 437 



the properties of the regular solids ; it was only necessary to 

 modify the distances of the old planets a little arbitrarily. 

 (" Non reperies novos et incognitos planetas, ut paulo antea, 

 interpositos, non ea mihi probatur audacia ; sed illos veteres 

 parum admodum luxates"* Myst. Cosmogr. p. 10.) The 

 ideal tendencies of Kepler were so analogous to those of the 

 Pythagorean school, and still more to those of Plato expressed 

 in the Timaus,] that in the same way as Plato (CratyL p. 409) 

 assumed, in addition to the differences of tone in the planetary 

 spheres, those of colour, Kepler likewise instituted some 

 experiments (A sir on. Opt. cap. 6, p. 261) for the purpose of 

 detecting the colours of the planets. Even the great Newton, 

 always so precise in his conclusions, was inclined, as Prevost 

 has already remarked (Mem. de VAcad. de Berlin, for 1802, 

 pp. 77 and 93) to reduce the dimensions of the seven colours 

 of the spectrum to the diatonic scale. 28 



quickly forsook them, to deceive himself with others. He 

 always retained a hopeful faith in being able to discover 

 numerical laws where matter had aggregated under the 

 manifold disturbances of attractive forces, (disturbances whose 

 combinations are incalculable, as are so many past events 

 and formations on account of our ignorance of the accom- 

 panying conditions) aggregated into globes, revolving in 

 orbits, sometimes simple and almost parallel, sometimes 

 grouped together and surprisingly complicated. 



* " You will not find new and unknown planets, as I said 

 before; that boldness I do not approve of; but you will find 

 the old ones a little altered in position." 



f Plato s Works translated, vol. ii. Bonn's Classical Library. 



28 Newtoni Opuscula Mathematica, Philosophica et Philo- 

 logica, 1744, torn. ii. Opusc. xviii. p. 246: " Chordam 

 musice divisam potius adhibui, non tantum quod cum pha3- 

 nominis (lucis) optime convenit, sed quod fortasse, aliquid 

 circa colorum harmonias (quarum pictores non penitus ignari 

 sunt), sonorum concordantiis fortasse analogas, involvat. 

 Quemadmodum verisimilius videbitur animadvertenti afiini- 

 tatem, quse est inter extimam Purpuram (Violarum colorem) 



L 2 



