Mar 4:12 That seeing they may see, and not perceive; and hearing they may hear, and not understand; lest at any time they should be converted, and [their] sins should be forgiven them.

Alternate version: That their seeing sees, but doesn't perceive and their hearing hears, but doesn't listen so they cannot turn themselves around and let go of their failures.

Here, Christ is making a reference to Isa 6:9 and Isa 6:10. The first few phrases reverses the pattern of hearing and seeing used in Isaiah. Why? Because Christ uses sight as the sense of the body and hearing as the sense of the mind. The whole point here is that you can physically see and hear but not comprehend with your mind. Christ was simply putting the words in an order that is more consistent with his use of symbols. We know this reversal in intentional because Christ does it elsewhere quoting this section of Isaiah.

Strangely enough, the contrasting wordplay here works better in the Greek (and in English) than it does in the original Hebrew. The Greek words for seeing and perceiving, blepô and eido, both primarily mean "seeing" but the first is more physical and the second with the sense of understanding. In the original Hebrew, the words , ra'ah meaning primarily "to see" and yada` meaning primarily "to know," the pun connecting them to sight is not as clear. In Greek, the word for hearing and understanding, akouô and suniêmi , also are both connected to hearing and have more of a connection the the original Hebrew shama` and biyn.

Though the second part of this verse seems to reference the next verse in Isaiah, it does not do so as closely as Mat 13:15, which quotes Isa 6:10 almost directly except, again, reversing the order of eyes and ears. Here, instead of speaking of being healed, Christ speaks of letting go of mistakes rather than of being healed.

This verse is interesting when thinking about questions about original sources for the Gospels, which Gospel came first, and whether or not Christ taught originally in Greek as well as Aramaic. Here, both Matthew and Mark capture the change of word order from Isaiah, but Matthew quotes Isa 6:10 almost directly, while Mark mixes elements of Isa 6:9 and Isa 6:10 and brings in new elements. Did one get it right and the other wrong? Or did Christ himself use the quote a little differently at different times, creating more than one version? However, in both versions we see the same word play that works better in Greek. Did two different translators working with two different original versions come up with the same word choices? Or was the original from the Greek with Christ making the puns?

"Seeing" and "see" are from blepô (blepo), which means "to look" and "to see." It is the more tangible sense of seeing, such as seeing what is right in front of you rather than understanding.

"Perceive" is from eido (eido), which is another word that means "to see," "to examine," and "to know." It has more the sense of understanding.

"Hear" and "hearing" are from akouô (akouo), which means "hear of," "hear tell of," "what one actually hears," "know by hearsay," "listen to," "give ear to," "hear and understand," and "understand."

"Understand" is from suniêmi (suniemi), which means "bring together," "come together in agreement," and, metaphorically, "to perceive" "to hear," "to take notice of" and "to understand."

"Lest" is from mêpote, which as a conjunction means "lest ever" and "that at no time."

"Converted" is from epistrephô, which means "to turn around," "to turn towads," "to cause to repent," and "to be converted."

"Sins" is from hamartêma (hamartema), which means "failure," "fault," and a "sinful deed." It is midway in meaning between adikêma, which means a "wrong done" or a "wrong" and atuchêma, which means a "misfortune" or "mishap."

"Forgiven" is from aphiêmi (aphiemi), which means "to let fall," "to send away," "to let loose," "to get rid of," "to leave alone," "to pass by," "to permit," and "to send forth from oneself." This is the same word that is translated as "leave" and "forgive" in the New Testament.