Genesis 9:21 Meaning

19These are the three sons of Noah: and of them was the whole earth overspread.

20And Noah began to be an husbandman, and he planted a vineyard:

21And he drank of the wine, and was drunken; and he was uncovered within his tent.

22And Ham, the father of Canaan, saw the nakedness of his father, and told his two brethren without.

23And Shem and Japheth took a garment, and laid it upon both their shoulders, and went backward, and covered the nakedness of their father; and their faces were backward, and they saw not their father's nakedness.