In the thirteenth prelude, F sharp major, here is lovely atmosphere, pure and peaceful.  The composer has found mental rest.  Exquisitely poised are his pinions for flight, and in the piu lento he wheels significantly and majestically about in the blue.  The return to earth is the signal for some strange modulatory tactics.  It is an impressive close.  Then, almost without pause, the blood begins to boil in this fragile man’s veins.  His pulse beat increases, and with stifled rage he rushes into the battle.  It is the fourteenth prelude in the sinister key of E flat minor, and its heavy, sullen-arched triplets recalls for Niecks the last movement of the B flat minor Sonata; but there is less interrogation in the prelude, less sophistication, and the heat of conflict over it all.  There is not a break in the clouds until the beginning of the fifteenth, the familiar prelude in D flat.

This must be George Sand’s:  “Some of them create such vivid impressions that the shades of dead monks seem to rise and pass before the hearer in solemn and gloomy funereal pomp.”  The work needs no programme.  Its serene beginning, lugubrious interlude, with the dominant pedal never ceasing, a basso ostinato, gives color to Kleczynski’s contention that the prelude in B minor is a mere sketch of the idea fully elaborated in No. 15.  “The foundation of the picture is the drops of rain falling at regular intervals”—­the echo principle again—­“which by their continual patter bring the mind to a state of sadness; a melody full of tears is heard through the rush of the rain; then passing to the key of C sharp minor, it rises from the depths of the bass to a prodigious crescendo, indicative of the terror which nature in its deathly aspect excites in the heart of man.  Here again the form does not allow the ideas to become too sombre; notwithstanding the melancholy which seizes you, a feeling of tranquil grandeur revives you.”  To Niecks, the C sharp minor portion affects one as in an oppressive dream:  “The re-entrance of the opening D flat, which dispels the dreadful nightmare, comes upon one with the smiling freshness of dear, familiar nature.”

The prelude has a nocturnal character.  It has become slightly banal from frequent repetition, likewise the C sharp minor study in opus 25.  But of its beauty, balance and exceeding chastity there can be no doubt.  The architecture is at once Greek and Gothic.

The sixteenth prelude in the relative key of B flat minor is the boldest of the set.  Its scale figures, seldom employed by Chopin, boil and glitter, the thematic thread of the idea never being quite submerged.  Fascinating, full of perilous acclivities and sudden treacherous descents, this most brilliant of preludes is Chopin in riotous spirits.  He plays with the keyboard:  it is an avalanche, anon a cascade, then a swift stream, which finally, after mounting to the skies, descends to an abyss.  Full of imaginative lift, caprice and stormy dynamics, this prelude is the darling of the virtuoso.  Its pregnant introduction is like a madly jutting rock from which the eagle spirit of the composer precipitates itself.