Reference : This stanza has been taken from the poem The Passing of Arthur composed by Alfred Lord Tennyson.
Context : The wounded King Arthur is going on his mysterious journey. He bids goodbye to his favourite knight Bedivere. He is very weak, so he speaks in a very low voice. He consoles him saying that he should not be sad on the ending of the age of chivalry.
Explanation : In this opening stanza the king Arthur speaks to Bedivere in a low voice, “Change is the law of nature. One thing does not remain the same at all times. The old systems change and new systems take their place. God also changes His ways in fulfilling His purposes. Even a good system may be harmful in the long run if a change is not brought in it in due course. One good system if it continues for a long time, may spoil the whole world.”