Pro 20:5 Counsel in the heart of man is like deep water; but a man of understanding will draw it out.
Ever heard the saying, "Still water runs deep"? Bet you didn't know that Solomon mentioned it first! I was reminded of drawing water from a well, too, by the last part of the verse.
In Bible times it was much harder to get water than it is today. Wells were considered extremely valuable, and fights (wars, really) would ensue over who owned them, or who had the right to draw water from them. Some of them were very, very deep. My study Bible notes that the well where Jesus spoke to the Samaritan woman (in John chapter 4) is thought to be Jacob's well, which was measured in 1935 at about 135 feet deep.
I think what Solomon is saying here, is that we need discernment (there's that word, again) to pull up the deep thoughts and emotions that are within a person's heart -- like trying to draw up the water from that deep well. Matthew Henry's study note on this verse gives the example of an individual who over many years and many life experiences, has built up a wealth of knowledge and wisdom. These are not usually the people who will scamper about and chatter about all that they know -- you need to draw them out. You do this by showing interest in them, by asking questions, and by thoughtfully probing (notice I did not say "prying" here) and in essence, letting down your bucket into the well.
Another place that this advice holds true is in our family relationships: have you ever thought to yourself, "I wish he (your hubby) would tell me how he feels!" Well, let's see . . . how can we let down a bucket into that well? Perhaps showing interest, and asking quiet questions (Have you had a bad day? How can I help?) and then being certain to listen, will allow us to draw out the thoughts and feelings of our spouse, and strengthen the bond of our marriage as well.
Lastly, do we need to let down a bucket, or to dive deep into another reservoir of wisdom? How about our Bible study time . . . do we need to set aside some time, ask some questions, and then listen for that still, small voice of wisdom?