PLATE 2(2) The last paragraph of the previous plate (the Lilly of the Valley) is best read together with this one (Thel's answer)
Right-click on the image and you will get a much larger scale
Picture. Or you may see it in the William Blake Archive; You
may see eight of them in fact. The Archive has 8 copies of
Thel (Blake made each of these illuminated poems individually.)
The Picture shows Thel in color under a tree (what tree?) the cloud
is grey, while Thel is a peach color (These colors undoubtedly had
distinctive significance for Blake. Ellie tells me that in Blake's
pictures of The Divine Comedy Dante's clothing was colored in red and
his teacher Virgil's was a bluish color. Looking at this picture we might
surmise that Thel was the protagonist, and the Cloud advised her.)
Here's the text of Plate 2:
(1) "Why should the mistress of the vales of Har utter a sigh.
She ceasd & smild in tears, then sat down in her silver
(2) Thel answerd. O thou little virgin of the peaceful valley.
Giving to those that cannot crave, the voiceless, the o'ertired.
Thy breath doth nourish the innocent lamb, he smells thy milky garments,
He crops thy flowers. while thou sittest smiling in his face,
Wiping his mild and meekin mouth from all contagious taints.
Thy wine doth purify the golden honey, thy perfume,
Which thou dost scatter on every little blade of grass that springs
Revives the milked cow, & tames the fire-breathing steed.(3)
(4) But Thel is like a faint cloud kindled at the rising sun:
I vanish from my pearly throne, and who shall find my place.
Queen of the vales the Lilly answerd, ask the tender cloud,
And it shall tell thee why it glitters in the morning sky,
And why it scatters its bright beauty thro' the humid air.
Descend O little cloud & hover before the eyes of Thel.
The Cloud descended, and the Lilly bowd her modest head:
And went to mind her numerous charge among the verdant grass."
(1) Har: A large variety of interpretations of Har is found in the literature.
Here's an extract from one of them:
"Damon believes that Har represents both the "decadent poetry of Blake's
day" and the spirit of conventional Christianity.
 Northrop Frye reaches a similar conclusion, but also sees divergence in
the character, arguing that although Har and Heva are based on Adam
and Eve, "Har is distinguished from Adam. Adam is ordinary man in his
mixed twofold nature of imagination and Selfhood.
Har is the human Selfhood. Har, never outgrows his garden but remains
there shut up from the world in a permanent state of near-existence."
 Harold Bloom agrees with this interpretation, arguing that "Har is
natural man, the isolated selfhood."
(From Har (Blake) in Wikipedia)
(3) This Thel seems to be uniformly benevolent. Never having been created or partaking in the fatal fruit of The Garden of Eden, there is no sin nor evil in her.
(4) But Thel is certainly aware of her evanescence and seems to hanker for something more; she hears the Queen of the Vales (perhaps Christ creating?). But obviously Thel was not ready to be created. (It's said that the nymphs and others in Eternity thirst for Creation; but who knows.)