Note 3 at Mk. 8:17: Just a few days before this instance, a hardened heart had made Jesus' disciples amazed when they saw Jesus walk on the water to them (see note 10 at Mk. 6:52, p. 179). Here, Jesus' statements reveal some of the characteristics of someone with a hardened heart.

First, a hard heart keeps us from perceiving spiritual truths. This is why everyone in a church service will hear exactly the same message and some will receive while others won't. It's not the Word that's the variable but rather the condition of the hearts (see note 2 at Lk. 8:11, p. 135). A hard heart stops spiritual perception (Examples: Ex. 7:10- 13,19-23; 8:8-15,16-19,31-32; 9:5-7,10-12,22-35; 10:13-20,21- 27; 11:10; 14:3-4).

Second, a hard heart stops us from understanding spiritual truths (1 Cor. 2:14). When a person doesn't understand God's Word, Satan finds no resistance when he comes to steal it away (Mt. 13:19; see note 3 at Lk. 8:12, p. 135).

Third, a hard heart keeps us from remembering. This isn't to say that we can't recall facts or scriptures because, as related in Mark 8:19-20, these disciples remembered the facts of the two miraculous feedings, but they had forgotten any spiritual lessons they may have learned. Likewise, some people can quote scripture or remember what the sermon was about, but they can't perceive the spiritual life in them or retain what they did perceive because of a hardened heart.

Also, in Job 39:13-17, God speaks of the ostrich as being hardened toward her young and equates that with being deprived of wisdom. A hardened heart towards God produces spiritual retardation.