Lexical usage

The construction involving ὑπό with the genitive can also indicate an instrument, if this instrument is conceived of as an agent.
Sometimes classical authors use other prepositions, depending on the meaning of the verb:

• ἐκ (Herodotus) or παρά (Attic) with ‘sending’ or ‘giving’;
• πρός (Herodotus) with 'thinking' or 'believing' (where Attic uses παρά with the dative).

Some writers have a very distinctive use of prepositions:

• Homer also has ἐκ or πρός with verbs of 'achieving' or 'reaching',
• Thucydides often uses ἀπό:
• with verbs such as λέγω to present two agents as being in opposition to each other;
• with verbs such as πράσσω to mark an indirect agent;
• Demosthenes often uses παρά;
• In Attic tragedy the monosyllabic prepositions ἐκ and πρός often occur under metric pressure;
• Bible translations such as the Septuagint sometimes use ἀπό to translate the Hebrew מִן min pr מֵא mē ('by', but also 'away from').

Historical background

From Homer until the 5th-6th century A.D. ὑπό with the genitive is the standard marker for the agent. After this period ὑπό is replaced by παρά in non-literary registers. From the twelfth century A.D. ἀπό gradually replaces παρά, to become the standard preposition in modern Greek.