@Quaestor Lucis said
"And yet, how about a horizontal one? Just to visualize the shaft following the motion of my hand? In this case the energy moves from Severity to Mercy, right? The meaning of this gesture - to anchor myself between the two polarities of the manifested world/my life (Malkuth), right?"
I wouldn't have put it that way AND I don't disagree with anything you said.
"Do I understand aright that the meaning of the entire phrase in Hebrew is something like this: "To Thee (Attah), o my Lord (Aiwass as HGA), I dedicate my life (Malkuth) in all its expressions (from Geburah to Gedulah)"?"
Literally (addressed to the HGA in the name Aiwass or its own name), "Thou, the Kingdom and the Strength and the Glory, world without end. So be it!" ("World without end" is a convention, dcode. L'olam literally means "toward the world," and functionally means, "through all the reaches of time and space.") There is no word for "dedicate," etc., though it's a nice thought ð
"I have not seen anything like this in the instructions from your "Pearls of Wisdom" ð Is it important? Should this one be the same size as the sphere above the head?"
That article was originally from a Beginners' column, and was meant to be tight, crisp, not burdening it with extra stuff other than literally how to do it. The next large block is best learned by months and years of doing the ritual. - In Temple of Thelema there are several papers that penetrate very deeply into the architecture, but these aren't public (though we talk about some of the content here and there, especially in response to direct questions).
The sphere at the feet may not register as a sphere - maybe usually it wouldn't - but energetically it's there. Small half-chakras (so to speak) exist in the instep of the each foot so that, when the feet are placed together - touching or nearly so - a full sphere snaps into place, the upper dome above the flood and the lower dome below. You don't need to know about it for this to happen, so it wasn't necessary to say anything about it (until you asked a specific question). - And the solar center at the heart (the Anahatta chakra) also is there whether you do anything about it or not.
Of course, one could argue that the same is true of Sahasrara, except that it is rarely all that obvious to most people, especially starting out. But we always mention it. I think the point is that getting that part right so important to the rest of the ritual that we need to make sure you know about it. The rest... mostly takes care of itself.