Of the sky

The sky is thought of as a clear, high, material dome, the  clouds  as  separate  bodies  suspended  beneath  it;  and  in consequence, however delicate and exquisitely removed in tone their skies may be, you always look at them, not through them. Now if there be one characteristic of the sky more valuable or necessary to be rendered than another, it is that which Wordsworth has given in the second book of the Excursion:

"The chasm of sky above my head
Is Heaven's profoundest azure; no domain
For fickle, short-lived clouds, to occupy,
Or to pass through; but rather an abyss
In which the everlasting stars abide,
And whose soft gloom, and boundless depth, might tempt
The curious eye to look for them by day."

...

And  if  you  look intensely at the pure blue of a serene sky, you will see that there is  a  variety  and  fulness  in  its  very  repose.  It  is  not  flat  dead colour, but a deep, quivering, transparent body of penetrable air, in which you trace or imagine short falling spots of deceiving light, and dim shades, faint veiled vestiges of dark
vapour."

.........

"The appearance of mist or whiteness in the blue of the sky is thus a circumstance which more or less accompanies sunshine,  and  which,  supposing  the  quantity  of  vapour constant, is greatest in the brightest sunlight. When there are no clouds in the sky, the whiteness, as it  affects  the  whole  sky  equally,  is  not  particularly noticeable. But when there are clouds between us and the sun, the sun being low, those clouds cast shadows along  and  through  the  mass  of  suspended  vapour.  Within the space of   these   shadows,   the  vapour,   as   above   stated,   becomes transparent and invisible, and the sky appears of a pure blue. But where  the  sunbeams  strike,  the  vapour  becomes  visible  in  the form  of  the  beams,  occasioning  those  radiating  shafts  of  light which    are    one    of    the    most    valuable    and    constant accompaniments  of  a  low  sun.  The  denser  the  mist,  the  more distinct and sharp-edged will these rays be; when the air is very clear, they are mere vague, flushing, gradated passages of light; when it is very thick, they are keen-edged and decisive in a high degree. "

The blessing of beauty

"...and yet it is not in the broad and fierce manifestations of the elemental energies, not in the clash of the hail, nor the drift of the whirlwind, that the highest characters of the sublime are developed. God is not in the earthquake, nor in the fire, but in the still, small voice. They are but the blunt and the low faculties of our nature, which can only be addressed through lamp-black and lightning. It is in quiet and subdued passages of unobtrusive majesty, the deep, and the calm, and the perpetual; that which must be sought ere it is seen, and loved ere it is understood; things which the angels work out for us daily, and yet vary eternally: which are never wanting, and never repeated; which are to be found always, yet each found but once; it is through these that the lesson of devotion is chiefly taught, and the blessing of beauty given. These are what the artist of highest aim must study; it is these, by the combination of which his ideal is to be created; these, of which so little notice is ordinarily taken by common observers, that I fully believe, little as people in general are concerned with art, more of their ideas of sky are derived from pictures than from reality; and that if we could examine the conception formed in the minds of most educated persons when we talk of clouds, it would frequently be found composed of fragments of blue and white reminiscences of the old masters."