The employment of bread and wine as the materials for this Sacrament--like the use of water in the Sacrament of Baptism--is of very ancient and general usage. The Persians offered bread and wine to Mithra, and similar offerings were made in Tibet and Tartary. Jeremiah speaks of the cakes and the drink offered to the Queen of Heaven by the Jews in Egypt, they taking part in the Egyptian worship.[342] In Genesis we read that Melchisedek, the King-Initiate, used bread and wine in the blessing of Abraham.[343] In the various Greek Mysteries bread and wine were used, and Williamson mentions their use also among the Mexicans, Peruvians, and Druids.[344] The bread stands as the general symbol for the food that builds up the body, and the wine as symbol of the blood, regarded as the life-fluid, "for the life of the flesh is in the blood."[345] Hence members of a family are said to share the same blood, and to be of the blood of a person is to be of his kin. Hence, also, the old ceremonies of the "blood-covenant"; when a stranger was made one of a family or of a tribe, some drops of blood from a member were transfused into his veins, or he drank them--usually mingled with water--and was thenceforth considered as being a born member of the family or tribe, as being of its blood. Similarly, in the Eucharist, the worshippers partake of the bread, symbolising the body, the nature, of the Christ, and of the wine symbolising the blood, the life of the Christ, and become of His kin, one with Him. The Word of Power is the formula "This is My Body," "This is My Blood." This it is which works the change which we shall consider in a moment, and transforms the materials into vehicles of spiritual energies. The Sign of Power is the hand extended over the bread and the wine, and the Sign of the Cross should be made upon them, though this is not always done among Protestants. These are the outer essentials of the Sacrament of the Eucharist. It is important to understand the change which takes place in this Sacrament, for it is more than the magnetisation previously explained, though this also is wrought. We have here a special instance of a general law.