"We rest; a dream has power to poison sleep"

   This lengthy quotation is from Percy Bysshe Shelley's Mutability, published in Alastor, or The Spirit of Solitude in 1816, well after the period in which the novel is set (See note to page 74)

From The Lyrics and Shorter Poems of Percy Bysshe Shelley, (J.M. Dent & Sons, Ltd., 1907):

 

We are the clouds that veil the midnight moon;

How restlessly they speed, and gleam, and quiver,

Streaking the darkness radiantly!--yet soon

Night closes round, and they are lost forever:

   

Or like forgotten lyres, whose dissonant strings           

Give various response to each varying blast,

To whose frail frame no second motion brings       

One mood or modulation like the last.  

  

We rest.--A dream has power to poison sleep; 

We rise.--One wandering thought pollutes the day;

We feel, conceive or reason, laugh or weep;  

Embrace fond foe, or cast our cares away:  

   

 It is the same!--For, be it joy or sorrow,

The path of its departure still is free:  

Man's yesterday may ne'er be like his morrow;

Nought may endure but Mutability.