Prelude at 
0:00
Fugue at 
4:07
This prélude et fugue, the second one from Dupré's op.7, is Imho one of his most poetic and touching works, very different from his late works which may sometimes sound a bit "dry bones", if I dare.  
For the prélude, the RH plays a singing and nostalgic melody under which the LH plays a quiet continuous garland of staccato 16ths on gambe 8' and octavin 2'. 
The "official" "Prélude de la goutte d'eau" (water drop prelude) is Chopin's 15th prélude in d flat,  but Dupré's one would surely deserve the same nickname. 
The fugue remains in the same quiet and dreamy mood, with a theme close from the prelude's theme. Its conclusion from 
8:37 is most moving, like a dream which ends. 
This prelude and fugue is surely the least difficult from op.7, but not so easy however :-)