There's a certain Slant of light,
Winter Afternoons –
That oppresses, like the Heft
Of Cathedral Tunes –
 - Emily Dickinson [full text]

When the light burst through in the forest, the word 'Cathedral' sprang to mind, with the tall, bare trunks as columns and the rays as if through an intricate window. 

Later, someone on facebook made a similar comment and pointed me to this poem by Emily Dickinson - the first stanza of which I've included.