Whilst I am writing, a remarkable phenomenon is passing along the sky.  The mists, which are shifting about and breaking in some places, allow you through their openings, as through skylights, to catch a glimpse of the blue sky, while at the same time the mountain peaks, rising above our roofs of vapour, are illuminated by the sun’s rays....

At Leukertad, at the foot of the Gemmi, he wrote (Nov. 9th): 

The clouds which gather here in this valley, at one time completely hiding the immense rocks and absorbing them in a waste impenetrable gloom, or at another letting a part of them be seen like huge spectres, give to the people a cast of melancholy.  In the midst of such natural phenomena, the people are full of presentiments and forebodings ... and the eternal and intrinsic energy of his (man’s) nature feels itself at every nerve moved to forebode and to indulge in presentiments.

On the way across the Rhine glacier to the Furka, he felt the half-suggestive, half-distressing sense of mountain loneliness: 

It was a strange sight ... in the most desolate region of the world, in a boundless monotonous wilderness of mountains enveloped in snow, where for three leagues before and behind you would not expect to meet a living soul, while on both sides you had the deep hollows of a web of mountains, you might see a line of men wending their way, treading each in the deep footsteps of the one before him, and where, in the whole of the wide expanse thus smoothed over, the eye could discern nothing but the track they left behind them.  The hollows, as we left them, lay behind us grey and boundless in the mist.  The changing clouds continually passed over the pale disc of the sun, and spread over the whole scene a perpetually moving veil.

He sums up the impressions made on him with: 

    The perception of such a long chain of Nature’s wonders, excites
    within me a secret and inexpressible feeling of enjoyment.

The most profound change in his mental life was brought about by his visit to Italy, 1786-87.  The poetic expression of this refining process, this striving towards the classic ideal, towards Sophrosyne, was Iphigenia.

Its effect upon his feeling for Nature appeared in a more matter-of-fact tone; the man of feeling gave way to the scientific observer.

He had, as he said (Oct. 30th, 1887), lately ’acquired the habit of looking only at things, and not, as formerly, seeing with and in the things what actually was not there.’

He no longer imputed his feelings to Nature, and studied her influence on himself, but looked at her with impersonal interest.  Weather, cloud, mountain formation, the species of stone, landscape, and social themes, were all treated almost systematically as so much diary memoranda for future use.  There was no artistic treatment in such jottings; meteorology, botany, and geology weighed too heavily.