Koheleth gives his personal experience of apparent confusion in the ordering of state affairs. There is an evil which I have seen under the sun. Power gets into the hands of an unwise man, and then errors are committed and injustice reigns.
As an error which proceedeth from the ruler. The כְּ here is caph veritatis, which denotes not comparison, but resemblance, the idealization of the individual, the harmony of the particular with the general idea.
The evil which he noticed appeared to be (he does not affirm that it is) a mistake caused by the ruler; it so presented itself to his mind. The caution observed in the statement may be owing partly to the tacit feeling that such blots occasioned difficulties in the view taken of the moral government of the world.
He does not intend to refer to God under the appellation "Ruler." The Septuagint renders, ὡς ἀκούσιον ἐξῆλθεν, "As if it came involuntarily;" Vulgate, to much the same effect, Quasi per errorem egrediens.
The idea here is either gnat the evil is one not produced by any intentional action of the ruler, but resulting from human imperfection, or that what appears to be a mistake is not so really. But these interpretations are unsuitable.
Those who adhere to the Solomonic authorship of our book see here a prophetic intimation of the evil of Jeroboam's rule, which evil proceeded from the sins of Solomon himself and his son Rehoboam. (So Wordsworth, Motais, etc.