Symbolism of water, blood, and spirit

"Also: The symbolism here used helps center our attention in the atoning sacrifice of the Son. The same elements were then present:

                "Spirit (in that our Lord voluntarily gave up the Ghost, permiting his spirit to leave the body)
                "Blood (in that he there completed the act, commenced in Gethsemane, of shedding his own blood for the sins of men)
                "Water (in that when one of the soldiers with a spear pierced his side...forthwith came there out blood and water. And he that saw it [John himself] bare record, and his record is true: and he knoweth that he saith true, that ye might believe.) (John 19:34-35)"