Son of the old Moon-mountains African!

• The poet starts the poem by comparing the river Nile to  a son, whose father is the Moon mountain range which is situated in Africa 
• John Keats directly addresses the river Nile adding an apostrophe to the sonnet
• Son is a metaphor which is a direct comparison to the river Nile, through which the poet attempts to add emphasis to its male characteristics. At the same time, the attribution of human characteristics can be seen as an anthropomorphism.
• old Moon-mountain range is the parent of the river Nile according to the poet, thus it can be introduced as a personification.

• The line ends with an interjection.

Chief of the Pyramid and Crocodile!

• Chief is a tribal leader, calling the river a chief reminds the reader of the African setting of the poem,and it can be considered as a metaphor as well as an anthropomorphism.
• The Egyptian setting is created through the visual images ,”Pyramid and Crocodile”,but Note that the poet doesn’t talk about the pyramids nor the crocodiles. It is the Pyramid and Crocodile. The definite article and the capitalization tells the reader that the Pyramid an the Crocodile are symbols 
• The line ends with an interjection.

We call thee fruitful, and that very while
A desert fills our seeing’s inward span:

• The comma(,) in the first line is a caesura which interrupts the flow of the line to give time for the reader to think on the mystery and obscurity of the river Nile.
• ‘thee’ is the archaic form of ‘you’ (object pronoun)
• The poet juxtaposes the ideas “fruitful” and the “desert” to further enhance the mystery of the river
• “seeing’s inward span” is the mind/imagination, the use of a lengthy description rather than using a single word can be introduces as a periphrasis

Nurse of swart nations since the world began,

• “Nurse” is the river Nile thus  It is a metaphor through which Keats attempts to illustrate how the river tended the (swart) dark-complexioned people and gave life to their civilizations.
• John Keats probable had no idea about the beginning of the world, therefor “since the world began” is a hyperbole

Art thou so fruitful? or dost thou beguile
Such men to honour thee, who, worn with toil,

• The poet asks the river whether it is truly fruitful or is it just enchanting (beguile) for the men who worked (worn) with extreme labour (toil) to honour it. as there is no answer,it becomes  a rhetoric question asked from the river which emphasizes  its obscurity.
• ‘thou’ is the archaic form of you (subject pronoun)

Rest for a space ‘twixt Cairo and Decan?

• ‘twixt is an ellipsis of which the complete word is betwixt. The modern English  meaning is  “between”
• Cairo and Deccan are two major destinations in the sea trade route between Asia and Africa; thus river Nile provided comfort for the weary travelers.
• The line is a question without an answer which is directed at the river. (rhetorical question)

O may dark fancies err! They surely do;

• The ninth line is the Volta of the sonnet which separates the octave (eight lines with a regular rhyming scheme) from the sestet (six lines with a regular rhyming scheme) 
• Keats comes to a conclusion that inaccurate (dark) imaginations (fancies) have made a mistake (err), by personifying the the ‘fancies’ which is later introduced with ‘they’
• with ‘O’ and the exclamation mark,the poet introduces an interjection to add emphasis to his sudden realization  

‘Tis ignorance that makes a barren waste
Of all beyond itself.

• the sonneteer remarks arousing the curiosity of the reader, that there is  an infertile waste regardless the earlier emphasized mythical value (Of all beyond itself) – which is caused due to the lack of knowledge 
• ‘Tis is an ellipsis which means ‘it is’

Thou dost bedew
Green rushes like our rivers,

• ‘dost’ is the archaic form of the verb ‘to do’
• Keats states that the river Nile covers the thick vegetation near the river(rushes) with water drops (bedew)
• as the river is performing the action of ‘bedew’ it can be taken as a personification
• green colour which repeats, emphasizes the prosperity of the river
• Keats uses a simile (like our rivers) to compare the river Nile to common rivers in Europe, which divests its mythical value 

and dost taste
The pleasant sunrise. Green isles hast thou too,

• The simile extends and the poet says, similar to the common rivers in Europe, the river Nile too enjoys the sunrise.
• the river performing the action of tasting is a personification
• The comparison extends and Keats mentions that like common rivers in Europe, Nile has islands (isles) in it too.

And to the sea as happily dost haste.

• The river being happy and hurrying (hast) are personifications.
• Note that the entire sonnet has a single period(.), which can be seen as an attempt of the sonneteer to illustrate the nonstop motion of the river which only halts at the sea.