Albert Barnes Commentary Job 12:3

"But I have understanding as well as you; I am not inferior to you: Yea, who knoweth not such things as these?" — Job 12:3 (ASV)

But I have understanding as well as you - Margin, as in the Hebrew, “a heart.” The word “heart” in the Scriptures is often used to denote the understanding or mind. It seems to have been regarded as the source of what was called life or soul. Indeed, I do not recollect a single instance in the Scriptures where the word “head” is used, as it is with us, as the seat of the intellect, or where the distinction so common with us between the head and the heart is referred to.

With us, the heart is the seat of the affections and emotions; with the Hebrews, it was the seat of understanding, and the σπλάγχνα (splangchna)—the viscera, the bowels—were the seat of the emotions (see the notes at Isaiah 16:11). A more correct physiology has taught us that the brain is the organ of the intellect, and we now speak of “the heart” as the seat of the affections. The Romans regarded the “breast” as the seat of the soul. Thus, Virgil, speaking of the death of Lucagus by the hand of Aeneas, says:

Tum latebras animae pectus mucrone recludit

Aeneid 10.601.

I am not inferior to you - Margin, “fall not lower than.” This is the literal translation: “I do not fall beneath you.” Job claims to be equal to them in the power of quoting the sayings of the ancients; to demonstrate this, he proceeds to adduce a number of proverbial sayings, occupying the remainder of this chapter, to show that he was familiar with that mode of reasoning and, in this respect, was fully their equal.

This may be regarded as a trial of skill and was quite common in the East. Wisdom consisted in storing up a large number of proverbs and maxims and in applying them readily and pertinently on all public occasions; in this controversy, Job was by no means disposed to yield to them.

Yea, who knoweth not such things as these? - Margin, “With whom” are “not such as these?” The meaning is that the sentiments they advanced, instead of being original, were the most commonplace imaginable. Job not only said that he knew them, but also that it would be strange if everyone did not know them.