Before G-d’s sovereignty will reign supreme (which will be the feature par excellence of the ultimate reality, as we’d said), it’s important to lay out the different ways G-d will have interacted with us from the first, which we’d cited above briefly.
He grants us pure physicality, which tantalizes the eyes and flouts its wares day after day . He also confers out-and-out spirituality to us, though it’s so rare. And He likewise allows us things that are a combination of the two, like the mostly though not purely spiritual things we referred to before, despite the calamitous materiality of the world .
But understand that the latter sort isn’t at all like the truly holy, as the mostly-spiritual is very different. For, while the purely spiritual is capable of undoing the darkness it’s that effulgent, the mostly spiritual just can’t do that. And that’s because while the mostly spiritual is an offshoot of pure holiness, to be sure, it’s nevertheless only that and no more.
For as we’d explained, the more abundant the presence of G-d is in a phenomenon, the greater the spirituality there, and the less abundant His presence, the less spiritual. So, when something is only mostly spiritual, only a limited amount of Divine presence was in it, which explains why it simply hasn’t the wherewithal to undo darkness. In any event, know that the allowance of pure materiality is just as much a miracle as that of pure spirituality and of the nearly-spiritual.
It’s also important to know that, invariably, one of the three predominates over the others at any given moment (be it purely material, spiritual, or mostly-spiritual), sometimes more and other times less so, depending on circumstances and G-d’s will. And each has its own consequences and ramifications, which then send off a slew of their own consequences and ramifications — and all according to G-d’s will.
Now, this switching-off between the spiritual, the profane, and the nearly-spiritual plays itself out most dramatically in specific time periods, like in the course of the Shabbat and the Holy Days as opposed to weekdays, for example. For, spirituality suffuses the Shabbat and the Holy Days and defines them, since G-d’s presence can best be sensed then; while weekdays are full of all sorts of mundane elements and themes simply because we can’t sense Him there all that much at those times .
 Though materiality is lower in grade than spirituality it still and all helps it perform. See this classical representation of the necessary partnership of spirit and material, body and soul: “Antoninus once said to Rebbe: ‘The body and the soul can both escape judgment! Why, the body can say: ‘It was the soul who sinned! From the day it separated from me I lie still like a stone in the grave!’ And the soul can say: ‘It was the body who sinned! From the day I separated from it I speed through the air like a bird (so why did G-d join them together?)'”.
Rebbe responded thusly: “To what can this situation be likened? To a human king who had a beautiful garden with fine figs in it. He set two guards over it, one blind and the other lame. Once, the lame guard said to the blind one: ‘I see fine figs in the garden! Come, give me a lift and together we’ll get them to eat!’ So, the lame guard rode on the back of the blind one, and they got the dates and ate them. Days later the owner of the garden came and said to them: ‘Where are those fine figs?’ The lame guard said: ‘Do I have feet to walk with (so how could I have taken it)?’ And the blind guard said to him: Do I have any eyes to see with (so how could I have taken it)?’ What did (the king) do? He lifted the lame guard onto the back of the blind one and judged them both as one. So too will the Holy One, blessed be He, bring the soul and place it in the body and judge them both as one” (Sanhedrin 91b).
For Kabbalistic references to this chapter see R’ Friedlander’s Iyyun 38 on p. 153 of his edition, R’ Greenblatt’s note 28, and R’ Shriki’s note 120.
 See 2:11, which referred to the five stages of universal and human development to which these three essential aspects allude.
 The same is true of specific times of the day as well, though Ramchal doesn’t address that here. The times we set aside for prayer, contemplation, Torah-study, and the like act as islands of the Shabbat and Holy Days in the course of the weekday.
Rabbi Yaakov Feldman has translated and commented upon “The Gates of Repentance”, “The Path of the Just”, and “The Duties of the Heart” (Jason Aronson Publishers). His works are available in bookstores and in various locations on the Web.