[§ 377]. When, now, well, worse, better—here the adverbial expression consists in a single word, and is simple. To-day, yesterday, not at all, somewhat—here the adverbial expression consists of a compound word, or a phrase. This indicates the division of adverbs into simple and complex.
[§ 378]. Adverbs of deflection may originally have been—
a. Substantive; as needs in such expressions as I needs must go.
b. Adjectives; as the sun shines bright.
c. Prepositions; as I go in, we go out; though, it should be added, that in this case we may as reasonably derive the preposition from the adverb as the adverb from the preposition.
[§ 379]. Adjectives of deflection derived from substantives may originally have been—
a. Substantives in the genitive case; as needs.
b. Substantives in the dative case; as whil-om, an antiquated word meaning at times, and often improperly spelt whilome. In such an expression as wait a while, the word still exists; and while = time, or rather pause; since, in Danish, hvile = rest.
El-se (for ell-es); unawar-es; eftsoon-s are adjectives in the genitive case. By rights is a word of the same sort; the -s being the sign of the genitive singular like the -s in father's, and not of the accusative plural like the -s in fathers.