Acts 10:11

And he beholdeth the heaven opened, and a certain vessel descending, as it were a great sheet, let down by four corners upon the earth; wherein were all manner of four-footed beasts and creeping things of the earth and birds of the heaven.

All manner ... is the significant word concerning all those creatures let down. In Leviticus 11, one may find a list of clean and unclean creatures, the latter being forbidden for Jews to eat; but the collection of creatures Peter saw was clearly remade up of many that were unclean. God was about to open Peter's eyes to the truth stressed by Paul, that "Every creature of God is good (to eat); and nothing is to be rejected, if it be received with thanksgiving, etc." (1 Timothy 4:4). Of course, this was no new doctrine "discovered" by the apostles; Jesus had plainly taught this, but it took a miracle to get Peter to believe it. See Mark 7:15-19. A similar thing may also be noted in the fact of Peter's Pentecostal declaration that the promise of the gospel was "to them that are afar off," plainly including the Gentiles; but the miracle before us was required before Peter could understand that this meant the Gentiles could receive the gospel without being circumcised and keeping the law of Moses.