The first 13 verses – Abhinavagupta

You are unsurpassed fullness, the beginningless transcendent reality beyond Māyā, [yet] You are the One who is seated in the cave of the heart of all the various living beings; the substrate of all, abiding in all things both moving and unmoving; [therefore] I take refuge in You alone, Benevolent One. || 1

Wandering bewildered through the cycle of suffering beginning with residence in the womb and ending with death [only to begin again], a disciple asked the blessed Lord who is the foundation [of all this] about that which is ultimately true (paramārtha). || 2

The Teacher answered him with the Stanzas on the Foundation [of Reality] (also known as the Essence of Ultimate Reality or Paramārtha-sāra).

The four [coexistent] Spheres—Energy, Māyā, Nature, and Earth—have each been brought into being and nourished by the Lord through the overflowing of the magnificence of his own powers. || 4

Within these [Spheres] is this universe, a continuum of wondrously diverse bodies, faculties [of perception and action], and the worlds [they perceive and act within]—and the experiencer of all of this is none other than Śiva himself in embodied form, having [voluntarily] taken on creatureness. || 5

Just as a flawless crystal takes on the appearance of various colors [when held before them], in the same way the Lord takes on the form of gods, humans, beasts, and plants. || 6

In moving water the moon’s image moves, and in still water becomes still. Just so is this Self, [a form of] the Great Lord, [inflected] in the classes of bodies, senses, and worlds. || 7

Just as the earth’s shadow, though unseen, is revealed [when] before the moon’s orb, even so this Self, though it in everything, is revealed in the mirror of the mind by means of its recourse to the sensual world. || 8

Just like a face appears in a stainless mirror, likewise this [Self] shines, expressing its radiance, in the mind made transparent by the touch of God’s grace aktipāta). || 9

Radiant, completely whole, full of joy due to reposing in itself, abundant with the [powers of] Willing, Knowing, and Acting, utterly replete with infinite power, free of all conceptualization, pure & clear, peaceful, never arising or dissolving: such is the supreme Reality within which appears this entire world [of our experience], consisting of thirty-six principles (tattvas)|| 10-11

Abhinavagupta invites you to contemplate the nature of this infinite Awareness that you are, with the list of descriptive qualities beginning with ‘Radiant’ and ending with ‘never arising or dissolving’. Though words cannot adequately describe its nature, these words point in the right direction. 

Just as [the images of] various things such as cities and villages reflected in a mirror are inseparable [from it], and yet appear [conceptually] distinct from each other and from the mirror, this world manifests without any separation from the flawless Awareness of Supreme Bhairava yet [seems] internally differentiated and different from [that divine Awareness]. || 12-13

My commentary: Abhinavagupta repeatedly uses the metaphor of a mirror in his work, because it is almost a perfect analogy to the nature of Consciousness, since the latter unifies all apparently disparate phenomena. Though all we see in a mirror is light reflected from a single surface, our brains carve up the image and label pieces of it as ‘my face’, ‘chair’, ‘table’, etc.—in fact you’re so accustomed to this that you easily forget the fact that you’ve never seen your own face directly. The reflection is your face, in your mental image of the world. In the same way, though everything is the Light of Consciousness, one easily believes in the appearance of separation amongst the objects one perceives, since perception is interpreted based on concepts that are themselves based on culturally-conditioned distinctions of name and form, when in reality there is only one continuous field of energy. Secondly, you easily believe in the separation of what you perceive from yourself, since you don’t notice that what you habitually call ‘me’ is just the most persistent and proximate reflection in the infinite mirror of your Awareness. In reality, everything you perceive is equally you, since it is all equally internal to your awareness.  

Make sense? No? If not, that’s because the mind has a really really hard time grasping a vision of reality that represents a completely different way of experiencing reality from how it was conditioned to see things. I thought about (and thought I understood) the everything-is-consciousness view for many, many years before I actually started experiencing it; and when I did, I was stunned at how totally I had failed to grasp it. It points you in the right direction; only the experience grants real understanding. To close, then, let’s consider another verse in which Abhinavagupta uses the mirror analogy, and you can just read it as poetry, tasting its resonance:
“The entire universe shines here within the Self, just as a complex creation [appears] in a mirror. However, awakened Awareness (bodha) consciously articulates the universe in accordance with the nectarean taste of its own self-reflection (vimarśa)—no mirror can do that.” (Tantrasāra)

Phenomenal experience arises through the union of apparently opposite principles, or, one could say, through the dynamic coherence of complementary polarities. 

– Hareesh