The comparison to plants "that flourish after rain" is meant to show
that

the progressive era is a period of widespread social activism and political reform across the united states that spanned from the 1890s to the 1920s.[1] the main objectives of the progressive movement were eliminating problems caused by industrialization, urbanization, immigration, and political corruption.

the movement primarily targeted political machines and their bosses. by taking down these corrupt representatives in office, a further means of direct democracy would be established. they also sought regulation of monopolies (trust busting) and corporations through antitrust laws, which were seen as a way to promote equal competition for the advantage of legitimate competitors.

many progressives supported prohibition of alcoholic beverages, ostensibly to destroy the political power of local bosses based in saloons, but others out of a religious motivation. at the same time, women's suffrage was promoted to bring a "purer" female vote into the arena.a third theme was building an efficiency movement in every sector that could identify old ways that needed modernizing, and bring to bear scientific, medical and engineering solutions; a key part of the efficiency movement was scientific management, or "taylorism".

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napoleon the third became a empire in 1873 also known as the era of the franco-prussian war.