Looked at from a higher perspective, there are a few interesting factors at work which we wish to mention. The blood, as we have pointed out many times, is the seat of the emotional responses as far as the body is concerned. The emotional responses arise initially in the astral body, but from there are passed to and stored in the physical blood supply. Of course, what is "stored," is not physical matter, and could not be discovered under the microscope. Nonetheless, the substance of the emotional responses-- much finer than gross physical matter, is carried throughout the body in the blood and thus is able to have its effect upon other organs as these are visited by the circulating plasma.
Now, in view of this fact, it will perhaps be apparent that when you accept the blood of another person, you also take into your body the emotional "charge," which the person's blood carried. Hence, is the donor was given to anger, resentment, bitterness or the like, you may find yourself more inclined toward these negative tendencies for a few days after the transfusion-the time duration being whatever is required for your body to transmute the negative emotional content of the accepted blood. It is for this reason that donors of blood should try to think only healing and loving thoughts while the blood is being withdrawn from their arm, and ideally should have such a positive disposition at all times.
Finally, we might point out that the passing of blood from one person to another through transfusion is a part of the program to unite all men as brothers. As each individual receiving a transfusion learns to transmute and "handle" the emotional content of the donor's blood, so he is also learning to handle his brothers' emotional states in general, to uplift these, and to understand his fellows.
As a postscript, we would mention that meat-eaters, consuming the blood of a slaughtered animal along with the flesh, also take into their bodies the anguish, terror and fear which the animal experienced at the moment of death. This emotional charge is not of a human variety, and is far more difficult to transmute and balance out than that found in a blood transfusion from a human being. The result of daily "injections" in fear laden animal blood is the build up of an extremely negative charge in the blood stream, which is constantly inciting negative emotions in the meat- eater. It requires more self-control for a non-vegetarian to master negative emotions than it does for one who avoids eating flesh of any kind.
Channeled through Maurice Cooke in Answers by Hilarion p. 100