Mat 13:15 For this people's heart is waxed gross, and [their] ears are dull of hearing, and their eyes they have closed; lest at any time they should see with [their] eyes, and hear with [their] ears, and should understand with [their] heart, and should be converted, and I should heal them.

Here, Christ is making a quoting Isa 6:10, but this is the first verse since I worked out the four hidden keys that refers to the keys' symbols. Hearts represent people's feeling, ears, the mind, eyes, the body. Christ reverses the original order of eyes and ears in Isaiah because Christ associates eyes with the physical body and ears with the mind. This reversal isn't accidental, we we see again in Mar 4:12 where Christ makes the same change when quoting Isa 6:9.

In the Greek, the words chosen make it clear that people are choosing not to see and not to hear, motivated by their spirit. What they fear is being "converted," that is "turned around" in the spirit, from the social (religion and tradition) to the internal (relationship with God). What is healed is the whole, everything is put back together working as it should.

Alternate versions: For this society's heart has become dense; ears are plugged to hearing, and eyes are shut, so that at no time should their eyes see, and their ears hear, and their hearts understand, and they turn themselves around, and make themselves whole.

"People" is from the Greek laos, which is a specific idea of "the people," meaning a specific group. It is the assembly of an troops or a tribe sharing the same name.

"Waxed gross" is from pachuno, which means "to fatten, "to grow fat," "to become thick," "to become dull," and is a metaphor for "to become stupid."

"Dull" is from bareos, which means "heavily," "pressed down," "with difficulty," and "weighed down."

"Closed" is from kammuo, which means specifically "to close or shut the eyes."

"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."

"Heal" is from iaomai which means "to cure," "to treat," and "to repair." Though in this case, I prefer Thayer's "to be made whole."