The subject of the infinitive, which in the longer form is denoted by a suffix, is in the case of the shorter form either not expressed at all in such a phrase as Isä antoi kirjan pojalle lukea, the father gave the boy the book to read; or it is put in the genitive. Isä toi kirjan pojan lukea, the father bought the book for the boy to read, literally for the boy’s reading.
The short form of the infinitive is used:—
(1) As the subject of impersonal verbs like täytyy, tulee, kelpaa.
Paha koira tarvitsee tappaa, one ought to kill a bad dog. Täytyy köyhän kärsiä, pitää kiittää päälliseksi, the poor must endure and give thanks into the bargain (proverbs). Sinun tulee puhua totta, you must speak the truth.
In this use two constructions are possible. One can say either talossa pitää olla isäntä, the master must be in the house, or Isännän pitää olla talossa. In this latter case the fact of the obligation affecting the person is emphasized, while the sentence with the nominative means rather, the master’s being in the house is necessary.
(2) As the complement of the verb olla combined with an adjective or substantive. Se kirja on hyödyllinen pojan lukea, this book is useful for the boy to read. Ei ole aikaa lähteä, it is not time to go. Pyyntösi on mahdoton kenenkään täyttää, your prayer is impossible for anyone to fulfil. Tämä kuorma on raskas sinun kantaa, this burden is hard for you to bear. On vaikea sanoa, it is hard to say.
(3) It is used to define the meaning of verbs. Talon mies ei osaa lukea, the farm servant does not know how to write. Alkaa sataa, it begins to rain. Laiska lapsi ei tahdo oppia, a lazy child does not want to learn. Hän ei ymmärrä puhua, he does not know how to speak. En voi tulla, I cannot come. Hän saa odottaa, he can wait. Aiotko viipyä täällä, do you mean to stay here. Sallitteko minun mennä? do you allow me to go? Klaus lähteä lupasi, Klaus promised to go (Kanteletar).
(4) It is used much like the longer form to express the object of an action. Tuo kala muidenkin katsella, bring the fish for others to see. Panen maata, I am going to bed. Onko teillä hevosta myödä? have you a horse to sell? Arvelevi miten olla kuin eleä, he considered what he should do, how he should live.
There is another use of this infinitive, when it is employed with a verb of kindred meaning in an adverbial sense. This use is very frequent in the Kalevala and poetry and occasionally found in prose. It is to be noted, however, that the infinitive generally represents what would be the principal verb in ordinary language, while the verb in the indicative indicates the manner in which the action is performed. Thus such a phrase as astua taputtelevi, means walking he stamped or he stamped as he walked. Härkä käyä källeröitti (Kal. xx. 43), equivalent to astui keveästi; cf. Astua lykyttelevi, Käyä kulleroittelevi (Kal. ii. 165). Waka vanha Wäinämöinen Ajoa karittelevi (Kal. viii. 18). Soutoa melastelevi (Kal. v. 41). Astua ajattelevi, Käyä kääpäröittelevi. Polttaa tuprutteli havannaansa.