I saw a lamb standing in the center near the throne. In the last verse we heard that the Lion of Judah had the right to break the seals, but now the story continues with a Lamb! Jesus is both Lion (the conqueror) and the Lamb (chosen to be sacrificed).
Then one of the leaders said to me, "Stop crying! The Lion from the tribe of Judah, the Root of David, has won the victory". It is probable that John knew the visions of Daniel where we read that the scroll was sealed up until the time of the end.