Change is the only constant thing in life. What is considered
to be good at one time, becomes a vice at other time. e.g.
travel to overseas was hated and people were boycott for it
(Recall how Mahatma Gandhi had to fight with his father for
going to England). Thus customes once considered to be good, do
not remain so-good later. Tennyson considers God is playing
with people and telling them how they were wrong earlier.

Poetry is the spontaneous process of the overflow of
powerful feelings : It takes origin from emotions,
recollected from tranquility.
- William Wordsworth