Mark chapter 4 presents the selective revelation of the secret of God’s kingship as a fact, but solutions to the problem of divine selection must be sought elsewhere. In so far as Mark 4 offers us any perspective on this problem, it lies in its insistence that an understanding of God’s way of governing his world is never likely to be achieved by unaided human observation and logic. Experience confirms that such understanding is ‘given’ rather than achieved by argument.
From R.T. France: “Divine Government: God’s Kingship in the Gospel of Mark” (Vancouver, BC: Regent College Publishing, ©1990, pgs 39-42). I’ve provided a much more extensive quote from this selection at the link above.