Darkness, a feature of the Universe, in scientific terms is a source of great mystery, for not only can it not be seen, it can't be identified either. Dark Matter makes a startling proportion of everything that exists, and yet it slips the net of observation every time, In a strange paradox, Darknesses of Mind are equally hard to fathom. (In the article linked, you'll find an interesting take on this.) Hard to identify, they fleetingly take hold and when they are gone, we wonder at their foundation. In feeling bright, gloom disappears. Nor is there much to explain why these transitions take place; as 'the blues' shout reasons for being there, in the same instant we can be telling ourselves all the reasons why we shouldn't be feeling this way.
In an enlightening Light, we see things from a positive perspective. In the darkest of thoughts, our perspective is negative. We live in a Universe (or an area of the Universe) dominated by negative Electrons, whose positive counterparts Positrons are annihilated as soon as they appear. In their annihilation, energy is produced, which leads me to believe that in the flux of our mental states, we orchestrate a balance between electrons and positrons all the time. In my early days of quantum investigation, I wondered why people are drawn towards cynicism, depression, anxiety... all kinds of negative mental states which sometimes even cost lives. When I found out about electron/positron annihilation, and the amount of energy expended in its process, I realised that feelings of joy, happiness and ecstasy come with a lot of energy we can use to good effect, while their negative opposites wear us out, leaving us 'feeling drained' and infecting others in contact to feel the same, hence the use of the term 'vampire' often used in this context.
Take no notice of those who tell you not to dwell. Go dwell. Dwell for as long as it takes - 'Dwell' isn't a bad word. When you've done dwelling, you'll find in the time taken to dwell (which might have seemed fruitless at the time), while answers have been rising to the surface and breaking into your thoughts like bubbles, the solutions have been riding along in the undertow waiting to find you.
Clarity comes in waves, to be muddied by emotions we don't necessarily want. But we need a dark/light balance, otherwise we are held fast by the illusions of one to the other - tricks of the light are as powerful as traps of blackness. Gems are in the Dark, gems of understanding and information. Sometimes it takes a mirror, someone else to see it for us, or something to happen that reflects the truth of our personal mysteries, before we can safely say we've cracked it. But when we do, we discover self-reliance. The energy of discovery lifts us above the tempest of need, attachment, loss and sorrow, all of which come down to an emptiness in the Self, and where an electron finds a well, it'll fill it with probability.
Trust those positrons, trust yourself, and trust that the way forward will come along when it's ready. when you've dwelt on it enough and given it time to mature. Where there is trust, there is Love, and where Love fills the spaces, those electrons may do their best.... but even in so doing, the energy from their collisions is a natural part of life's refuelling process, so the fear that accompanies the darkness of negativity can only hold for so long once Beauty and Truth are given their rightful places at the helm of whatever comes next.