Excerpt from Byzantine Book of Prayer:
For instance, in primitive religions, there was a strong distinction between the “sacred” and the “profane”. In this context, a blessing transferred its object from the realm of the profane to that of the sacred.
In a truly Christian view, however, this type of the distinction between the sacred and the profane disappears, for the whole world and everything in it has been created by God—and He saw that it was all “good,” as the Book of Genesis reminds us. To bless something in this way of thinking means to acknowledge that it is truly good, that it comes from God ; it means that we see this blessed object as a sign of God’s presence among us. To bless, then, means to see things as they really are—as coming from God—and to acknowledge Him as the Source of all good.
The blessing of fruit, water, etc., means that these objects become visible signs of God’s presence in our lives. We can then “see beyond” the actual object, to a whole new world of God’s kingdom.