Nolland, Luke 1–9:20, p. 97. The Greek here refers to not merely storing up ideas, but valuing and evaluating them, ruminating on them because their meaning is not immediately apparent. This would be the opposite of someone who is hard-hearted and immediately rejects the message. See the discussion in Ben Witherington III, Women in the Ministry of Jesus (Cambridge: Cambridge Univ. Press, 1987).