of its own accord: coming about with no outside help and no human hand behind it
The Greek word automatos means roughly what it looks like: self-moved. It joins the word for "self" to an old root for eagerness or impulse, so it describes something that comes about on its own, with nothing outside pushing it along. English "automatic" and "automaton" descend straight from it, which is a helpful hint and a trap at once, since the Greek carries no suggestion of machinery.
The word appears only twice in the New Testament, and those two verses happen to be its two oldest and most familiar uses. In Mark 4:28 a farmer scatters seed, sleeps and rises night after night, and the ground bears fruit by itself while he has no idea how. In Acts 12:10 an angel walks Peter out of prison, and the iron gate into the city swings open with nobody at the latch.
In neither place does the word say the event had no cause. It says the event had no human cause, and that is the point the reader is meant to follow up. The farmer contributes nothing to the growing, and Peter and his escort touch nothing. Both writers leave the missing human hand in plain view so that the reader looks past it to God's.
Greek-speaking readers of the Old Testament already knew the word from the harvest laws. In a sabbath or jubilee year Israel was not to sow or reap, and whatever came up unplanted, the grain that springs from last year's seed (סָפִיחַ), was to be left standing (Leviticus 25:5, 11); the same unsown growth is promised to Hezekiah as a sign (Isaiah 37:30). That is the older language a first-century reader would have heard behind Mark's field that produces on its own.
Nuances
Whether Mark's "of its own accord" deliberately echoes the Greek Old Testament wording for the crop that comes up unsown in the sabbath and jubilee years (Leviticus 25:5, 11).
- majorityThe verbal overlap is natural agricultural vocabulary rather than a pointed citation. The parable's accent falls on growth apart from human effort and understanding, and on the certainty of the coming harvest.; R. T. France, The Gospel of Mark (NIGTC), Eerdmans, 2002, on Mark 4:26-29; C. E. B. Cranfield, The Gospel according to Saint Mark (CGTC), Cambridge, on Mark 4:26-29
- minorityThe wording is a deliberate allusion to the sabbatical and jubilee harvest, giving the parable a jubilee resonance in which God supplies the increase while human hands rest.; J. J. Scholtz, on the sabbatical-year background of the parable of the growing seed