According to the Gospel of John once Christ had died on the cross “one of the soldiers pierced His side with a spear, and immediately blood and water came out” (19:34).
Many would overlook such a simple detail. However, many have viewed it to be quite remarkable given modern medical knowledge not known to John’s author in his day. According to medical science the combination of shock, a rapid heart rate, and heart failure results in a collection of clear, watery fluid around the heart and lungs (1). As such, an incision through the lung and heart would release that fluid as well as blood. It appears that this is what John’s author is speaking about based on an account of an eyewitness who likely saw what John narrates.
This small detail not only suggests the likeliness that an eyewitness recounted what he actually saw happened, but it also has wider implications for the passion story. If Christ’s side was pierced it would suggest that he was crucified, and that he died on the cross, both of which feed into the wider passion story of Christ’s trial, burial, and resurrection.
1. Edwards, W. 1986. Journal of the American Medical Association. p. 1463.