The Emanator, blessed be His name, instituted a certain law whereby the substance of the creations remains unchanged yet their soul may nevertheless be increased within them, giving them a higher status even though their body does not change. This is the Additional Soul given to man. Correspondingly in the higher realm too He instituted in the Sefirot the phenomenon whereby their exterior – which is the root of man’s body – receives an interior soul beyond what is due to it according to its intrinsic nature, and this is called an ascent for it.
As long as it is in the process of receiving its due, this is called growth towards completion. What is above this is an ascent. There are various arrangements like these, for this is the source of the addition that comes at different times on weekdays, Shabbat and the other holidays.