⏑−⏑−¦−⏑⏑¦−⏑−−¦¦⏑−⏑−¦−⏑⏑¦−⏑−− Upajāti (Chāyā)
tataḥ sa bālārka ivodaya-sthaḥ samīrito vahnir-ivānilena
krameṇa samyag-vavdhe kumāras-tārādhipaḥ pakṣa ivātamaske || 2.20
And so, like the early-morning sun on the way up,
Or like a fire being fanned by wafts of air,
Gradually, the child developed well --
Like the waxing moon in the bright fortnight.
In a footnote to his translation of today's verse EHJ noted that all three similes exemplify the ordered growth of brightness.
That comment is spot on. And going further, the similes of the rising sun, the burning fire, and the waxing moon may all be understood to exemplify growth that, immune to human interference, does itself. This is in line with the gist of yesterday's verse as I understood it – namely, that growth of a child is not something that even the best of mothers can bring about by direct means.
The great principle of indirectness is that if we stop doing the wrong thing, the right thing tends to do itself. This is the fundamental principle, the essence of the universal precept of the Seven Buddhas, Gautama Buddha's main thesis.
And yet, although the fundamental principle is non-interference, the fact in reality may be that sometimes the right thing needs (in addition to a lot of effort to get going) a bit of help to keep going. The simile of the fire being fanned by wafts of air, therefore, can be taken not only as an expression of the fundamental thesis but also as a suggestion of a concrete counter-example, representing the antithesis -- depending on what or who is doing the wafting.
Either way, the verse as a whole suggests that the young prince was subject to the lightest of light-touch regulation, and that nothing was forced or hurried, but the right thing was rather allowed to do itself.
Digging deeper, why is the simile of the moon given pride of place in the 4th pāda?
Maybe because the rising sun and a burning fire generate their own heat and light, whereas the waxing moon just coolly reflects.
tataḥ: (ind.) then, thence, on that basis,
sa (nom. sg. m.): he
bālārkaḥ (nom. sg. m.): the newly-risen sun
bāla: mfn. young ; newly risen , early (as the sun or its rays)
arka: m. ( √ arc. to shine) a ray , flash of lightning ; the sun
udaya-sthaḥ (nom. sg. m.): on the way up; on the eastern mountain
ud-aya: m. going up , rising; rising , rise (of the sun &c ); the eastern mountain (behind which the sun is supposed to rise)
stha: mfn. standing , staying , abiding , being situated in , existing or being in or on
samīritaḥ (nom. sg. m.): mfn. stirred , moved
vahniḥ (nom. sg.): m. any animal that draws or bears along , a draught animal ; the conveyer or bearer of oblations to the gods (esp. said of agni , " fire " , or of the three sacrificial fires); fire
anilena (inst. sg.): m. air or wind, god of wind
√ an: to breathe, respire, gasp ; to move, go
krameṇa: (ind. instr.) in regular course , gradually , by degrees
samyak: ind. in one or the same direction ; completely , wholly , thoroughly ; correctly , truly , properly , fitly , in the right way or manner , well , duly
vavṛdhe = 3rd pers. sg. perf. vṛdh: to grow , grow up , increase
kumāraḥ (nom. sg.): m. child, boy, youth; the prince
tārādhipaḥ (nom. sg. m.): = tārakā-rāja: m. " star-king " , the moon
tārā: f. a fixed star , asterism
adhipa: m. a ruler , commander , regent , king.
pakṣe (loc. sg.): m. wing, side; the half of a lunar month (the first half from new moon to full moon was called pūrva or apūryamāṇa , later śukla or śuddha ; the other half apara or apa-kṣīyamāṇa , later kṛṣṇa or tāmisra ; each fortnight consists of 15 tithis or lunar days called prathamā , dvitīyā &c)
a-tamas-ke (loc. sg. m.): mfn. without darkness, bright