Q: Despite all the explanations, there is something I still don’t understand: is the vessel a desire, or an aim?
A: A vessel is a desire that receives Light, the response from the Creator. It is the intent not to act “for me,” but for interests beyond my own. That is why we don’t consider the mere desire to be a vessel, but rather the screen, the altruistic aim to bestow, the returning Light.
Q: Is there something that does not let the Light inside the vessel, but only creates an opening, without which the Light cannot enter?
A: The Light is the Creator. We always speak from the perspective of the vessel, the creature. Any other perspective that is not from the sensation of the vessel is unfounded. In the state of Ein Sof (infinite), after the vessel receives the Light for itself (in order to receive), it decides never to do it again. It decides to restrict the reception of Light in its own desire to receive for itself.
That is called the “first restriction.” From that state down to this world, all the vessels wish not to receive Light in order to receive. In other words, the law of the first restriction is kept in all the degrees. The power to keep the restriction is called a “screen,” because it protects the desire from using the Light for self-profit. But other than that, there is another screen – not just for maintaining the restriction, but also for receiving the Light for the Creator.