Note 14 — Section 120. DO GOOD IN YOUR OWN SPHERE OF ACTION. II.
Reading edition
is most so = is most important.—When the superlative is used as a predicate, it is generally preceded by am (the preposition an contracted with the definite article, dative case singular, masculine), and takes the dative termination en; as—This matter is not important, but that is most important, diese Sache ist nicht wichtig, aber jene ist am wichtigsten.