Final answer:
The use of antithesis emphasizes the contrast between the past and present, such as comparing America in different time periods, to underscore changes and highlight themes like freedom versus societal constraints.
Step-by-step explanation:
The use of antithesis in the statement “the world is very different now” serves to highlight the dichotomy between the present and the past. By setting up a juxtaposition, the speaker emphasizes how drastically things have changed over time. For instance, comparing America in 1961 with America in 1776 underscores the evolution in social, political, and technological realms. This literary device can also bring attention to contrasting feelings or themes within a text, such as freedom versus oppression or innovation versus tradition. Thoreau’s legacy is a prime example of how antithesis can frame a concept like freedom by contrasting personal liberties with societal constraints. In the broader context of textual analysis or social commentary, antithesis can be employed to starkly delineate different perspectives, such as those arising in a polarized society. When discussing literature, antithesis may be noted in the contrast of thematic elements, as in the comparison between the limitations imposed by governmental restraints and the pursuit of self-realization, as is the case with the analysis of Thoreau's essays on freedom.