This is really two quotations in one. The more famous element
ends after 'equal'. Most non-Americans would be hard-pressed
to continue the quotation and get as far as 'happiness'. But
the plural form 'truths' shows that there is more to be said
than just the point about equality, and this motivates the longer
version. There are few quotations which exceed this one for
general applicability; and few where it has proved so necessary
to keep asserting the insight it expresses.