One part in particular has shined a light onto my thoughts and feelings this summer:
If I say, "Surely the darkness will overwhelm me,
And the light around me will be night,"
Even the darkness is not dark to You,
And the night is as bright as the day.
Darkness and light are alike to You.
(Psalm 139:11-12)
What stands out to me in these verses is the contrast between the Psalmist's perception of reality and God's perception of it. David (the Psalmist) writes that he may very well feel overwhelmed by his circumstances. In fact, much like me quite frequently, he is anticipating feeling overwhelmed in the future, rather than expressing an emotion immediately present. I relate to this as a feeling of anxiety: worry about the future and the possibility of feeling overwhelmed by it.
By contrast, David recognizes that God has no such apprehension. To God, there can be no overwhelming circumstance. To God, light and dark are not even materially important. He is in charge of all things and knows all things, so night brings no unknowns, surprises, fear, or anxiety.
A few lessons are helpful to me here. First, David struggled with some of the things I struggle with. I'm not alone. Second, what he did with the struggle is what I should do: he prayed about it (since the psalm is essentially a prayer to God). Third, David recognized when he was not yet feeling overwhelmed the truth that God is sovereign, so that when he did feel overwhelmed, he could remind himself of this truth. The time to nail down the truth of God's power and comfort is now; I should take advantage of the mentally clear times to prepare for times that are more challenging emotionally by reflecting on truth.
Fourth, David says that he may perceive light to be night. In other words, his perception may be faulty. I think emotional distress or depression can cause us to perceive reality incorrectly. Even joyful things lose their luster when our distress takes over. On the other hand, God, who is perfect, perceives even the "dark" circumstances with total authority and control, directing them for His own purpose and His glory (also, as Paul writes, for the good of those who love Him, whom He has called!). His perception of reality is reality; He can never be mistaken.
I, along with David, can take comfort in His sovereignty. He is absolute truth, and reality is dependent on Him. He is wise and good, and He is loving, just, merciful, patient, gentle, powerful, and so many other wonderful things so perfectly that I cannot possibly comprehend Him altogether. Therefore, when my emotions are askew, and even good circumstances feel off somehow, and when I feel overwhelmed by challenges, let me remember the truth: God always sees light even if it is dark, and God always sees me, so in some sense I am always in the light.
Of course, Jesus is also called the Light, and if I am in Him, through faith in His sacrifice and resurrection on my behalf, I am in the Light in an eternal sense as well: I am always and forever in the Light. Nothing and no one can take this away.