passover

For a more in depth discussion on the topic of hyssop, "it is finished" and the passover, I strongly recommend listening or reading the book, "The 4th Cup" by Dr. Scott Hahn. You will be surprised of the historical significance of everything that was done...starting at the last supper.
You can listen to a podcast at this link: http://catholicmentoday.org/2009/01/07/the-fourth-cup-by-dr-scott-hahn.aspx

Scott Hahn is a name that probably won't mix too well with SI.

http://www.bereanbeacon.org/apologists/The_Desire_of_Scott_Hahn.pdf

http://www.bereanbeacon.org/apologists/The_Damnation_of_Scott_Hahn.pdf

http://www.bereanbeacon.org/apologists/The_Lost_Soul_of_Scott_Hahn.pdf