Mention two things that are

(i) clear from the height.

(ii) not clear from the height

(i) When the aeroplane was six miles from the ground, it was clearly visible that the earth was round. Also, because of the general blue hue and view of sea, it was evident that the earth had more sea than land.

(ii) The boundaries that divides places geographically, e.g. walls after cities, borders of countries were not visible from that height and the poet wondered why people fight over such petty matters.