Regarding the sheep who lie down, I was listening to James Montgomery Boice exposit the 7th chapter of Micah, verse 14.
Shepherd your people with your staff, the flock of your inheritance, which lives by itself in a forest,
in fertile pasturelands. (Micah 7:14)
Mr Boice explained about the Shepherd and the sheep. He said that he had heard, but did not know if it was true, that sheep won’t lie down until their needs are met. Only when they are full, their thirst slaked, and their surroundings peaceful, will they rest. I began looking that up because having lived next to a flock of sheep for the past year, I like looking at them and learning their qualities so as to better understand the Bible’s use of them as an example. O.P. Gifford, Pastor of First Baptist Church of Brookline MA in 1909, wrote an exposition of the Twenty Third Psalm for the Homiletic Review Minister’s Monthly. Pastor Gifford remarked-
A sheep has four stomachs. When its first stomach is full, he will lie down and ruminate, that is, chew his cud so that it can pass to the second stomach. But it will still not lie down if there is restlessness within the flock, or if there is friction between sheep family members, or if there is a predator. A lying down sheep means he is full, peaceful, and content.
Here is an excerpt from Pastor Gifford regarding the still waters:
The pictures in the Bible are tremendous for allowing us to see biblical truths, no matter our age, culture, or epoch in which we live. I look forward tot he day when I can lie down, thirst slakes, hunger dismissed, and no friction in the flock, and no predators. Ahhh, the Lord is good, or should I say the Good Shepherd is good!