Final answer:
The theme of 'freedom' in relation to 'happiness' for all beings is evident in literature wherein characters or narrators express a longing for an unconstrained existence.
Step-by-step explanation:
The poem The Trees likely deals with the idea that freedom is essential to the happiness of all living beings, as suggested by various poems and texts that link freedom with a natural state of contentment and well-being. For example, Claude McKay's poem In Bondage yearns for a distant, idyllic setting where freedom allows for a leisurely existence and the earth yields her gifts freely.
Similarly, the exalted cherry trees in Loveliest of Trees, clothed in white for Eastertide, could be seen as a metaphor for renewal and liberation, resonating with the theme of freeing oneself from societal restraints as explored by Thoreau in his works on individual freedom and civil disobedience. Exercising freedom, whether by breaking free from conventional social norms or governmental control, is presented as a way to reach a state of happiness, and it drives the thematic exploration in these literary pieces.