Although this is a small paperback that you used to be able to find in Dollar stores (which is where I originally got it and gave it to my late husband), it's a powerful but very readable compilation of some of very sound Biblical teachings by famous Christian author/apologist Andrew Murray. I highly recommend it for anyone who wants to grow closer to The Lord and learn to communicate with Him in the way He has set forth for maximum communion.
A wonderful 6 month devotional on prayer.