Today marks the 1st day of Passover and the 50 day countdown to Pentecost. In the book of Exodus chapter 12, Moses instructs the Jewish people to place the blood of a lamb on their door in 3 places in order to avoid the destroyer.
And ye shall take a bunch of hyssop, and dip it in the blood that is in the bason, and strike the lintel and the two side posts with the blood that is in the bason; and none of you shall go out at the door of his house until the morning. For the LORD will pass through to smite the Egyptians; and when he seeth the blood upon the lintel, and on the two side posts, the LORD will pass over the door, and will not suffer the destroyer to come in unto your houses to smite you. Exodus 12:22-23
If we draw a line from each point on the door the blood was put, it would look like this.
It makes a triangle pointing up towards Heaven and represents the act of man looking towards God. Now fast forward to around 32 AD. Christ dies on the cross for all mankind leaving blood on the cross at the hands and feet.
Connecting the dots we can see an upside down triangle pointing down as a sacrifice from God to man.
Combine the two triangles and we have:
And I will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me whom they have pierced, and they shall mourn for him, as one mourneth for his only son, and shall be in bitterness for him, as one that is in bitterness for his firstborn. Zec 12:10