"The Stolen Boat" from William Wordsworth's The Prelude

One summer evening (led by her) I found 
A little boat tied to a willow tree 
Within a rocky cave, its usual home. 
Straight I unloosed her chain, and stepping in 
Pushed from the shore. It was an act of stealth 
And troubled pleasure, nor without the voice 
Of mountain-echoes did my boat move on; 
Leaving behind her still, on either side, 
Small circles glittering idly in the moon, 
Until they melted all into one track 
Of sparkling light. But now, like one who rows, 
Proud of his skill, to reach a chosen point 
With an unswerving line, I fixed my view 
Upon the summit of a craggy ridge, 
The horizon's utmost boundary; far above 
Was nothing but the stars and the grey sky. 
She was an elfin pinnace; lustily 
I dipped my oars into the silent lake, 
And, as I rose upon the stroke, my boat 
Went heaving through the water like a swan; 
When, from behind that craggy steep till then 
The horizon's bound, a huge peak, black and huge, 
As if with voluntary power instinct, 
Upreared its head. I struck and struck again, 
And growing still in stature the grim shape 
Towered up between me and the stars, and still, 
For so it seemed, with purpose of its own 
And measured motion like a living thing, 
Strode after me. With trembling oars I turned, 
And through the silent water stole my way 
Back to the covert of the willow tree; 
There in her mooring-place I left my bark,-- 
And through the meadows homeward went, in grave 
And serious mood; but after I had seen 
That spectacle, for many days, my brain 
Worked with a dim and undetermined sense 
Of unknown modes of being; o'er my thoughts 
There hung a darkness, call it solitude 
Or blank desertion. No familiar shapes 
Remained, no pleasant images of trees, 
Of sea or sky, no colours of green fields; 
But huge and mighty forms, that do not live 
Like living men, moved slowly through the mind 
By day, and were a trouble to my dreams