Mystery and music: The earth has many keys - A poem by Emily Dickinson

Here is an Emily Dickinson poem on the mysteries of our world.  The origins of beauty are mysterious.  And what better way to desribe a mystery than through the element of music.  Emily claims that the mystery behind Earth's beauty is unknown.  But we can find signs of the mystery if we can hear the cricket singing about the lands, the seas, the peninsulas and keys.

The earth has many keys,
Where melody is not
Is the unknown peninsula
Beauty is nature's fact

But witness for her land
And witness for her sea
The cricket is her utmost
Of elegy to me

key
Noun
1. small piece of shaped metal, with incisions cut to fit the wards of a particular lock, that is inserted into a lock and turned to open...
2. low-lying island or reef, esp. in the Caribbean.

el·e·gy
/ˈeləjē/
Noun
1. poem of serious reflection, typically a lament for the dead.
2. piece of music in a mournful style.