" It expresses a parallel relationship. There's the old adage about US voting habits: As Maine goes, so goes the country. Who(m)ever the state of Maine votes for, the country as a whole will also vote for.
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Darcy * Just as the old have need of energy of youth, so the young have need of the experience of old age.Edit. I suppose in this case you might say "conversely" rather than "similarly," since it has a strange twist.