The infinitive in Finnish is a real substantive, that is to say, just as from a verbal root can be derived, by the addition of suffixes, forms expressing person, time, and modality, so by the addition of other suffixes to the same root can be formed nouns, which can take the ordinary case terminations and also the pronominal suffixes.
These infinitives are five in number. Their signification and use, which constitute one of the great difficulties of the Finnish language, will be explained in the Syntax.
I. The termination of the first infinitive is -taʻ (-tä), e.g. saada (rule [32]); root nous (for nouse), nousta; root tul (tulee), tulla. Between two simple vowels this t drops out and the termination is simply a (ä); sano-ta, sanoaʻ; repitä, repiä. N.B.—The syllable ta (tä) or a (ä) is closed with the aspiration.
This infinitive has only one case, the translative, which is used with the personal suffixes, e.g. juo, to drink, juo-da-kse-ni, for my drinking, lukeaksesi, for thy reading.
II. The stem of the second infinitive is formed by adding -teʻ to the root, the syllable being closed. This te becomes e between two simple vowels like the ta of the first infinitive. It has as a rule only two cases, the inessive and instructive (though some verbs have more), to which the personal suffixes can be added, e.g. saa, saade, saadessa, saadessani (in my receiving); instructive saaden. Tule, shortened root tul, infinitive II tulle, inessive tullessansa, instructive tullen; repi, infinitive repie, repiessä, repien.[10]
III. The third infinitive is formed by adding ma (mä) to the root. There is nothing irregular in its formation or declension. It is used in most of the cases of the sing., but only occasionally takes the personal suffixes, e.g. sano, infinitive III sanoma, genitive sanoman, sanomalla, sanomatta, etc., exactly like a noun.
IV. The fourth infinitive is formed by adding mise to the root. It has two cases, the nominative which ends in minen, and the partitive in mista. Sano, sanominen, sanomista; teke, tekeminen, tekemistä, tekemistänsä, etc.
V. The fifth infinitive, which is not much used except in poetry, and may be regarded as a diminutive derived from infinitive III, is formed by adding maise to the root. It is used only in the adessive plural, and always with a personal suffix. Nouse, to rise, nouse-mais-i-lla-nsa; tule, tulemaisillani.
There are two participles or verbal adjectives in Finnish. They are simply adjectives formed from a verbal root by the addition of a suffix.
I. The first verbal adjective is formed by adding va (vä) to the root. (Sometimes this suffix is found in the form of pa, pä.) The adjective so formed is declined in the ordinary way.