The Meor Eynayim explains that all the best things in life actually come from the highest realms, and so, praying for them takes the most effort, because there are so many gates to bring them down through in order to reap the benefits down here in this, the lowest of worlds.
Things like, children, a proper (shidduch) match, parnasa, rain, refuah (healing) they all derive from the highest purest supernal light.
I want to go into the details a little of what this means and what it can teach us, and then perhaps deviate on a tangent.
Drawing down HaShem's blessing in any form can always be referred to and described as a yichud , a union. Just as getting something from someone else requires relating to them in some way in order to elicit what you want, so too, receiving blessing from HaShem follows parallel 'rules.'
Here though, the process of drawing down divine light differs from obtaining things from other people. In our world, people are created in such a way that everything is exterior to ourselves. If you want money from your employer (or your parents) you ask them for it and they reach into their wallet and produce it. If you want a candybar, the store owner hands it to you from the shelf, etc.
It's only when we get into more intimate human interactions that it ceases to be a relationship of objects exterior to oneself. Let's say you want to know what your friend is thinking, or you want to hear a story, then the person needs to reach inside themselves and produce something for your. In the process they enter the recesses of their intellect or the depths of their heart, and then take that thought or feeling and winnow it down into words and sentences. Finally they turn those words and sentences into sounds through the use of their mouth and you get to hear whatever they choose to tell you.
When it is money or merchandise or clothing or anything else exterior, we can always take that thing by force. But when it is something that exists only within the person, we have to find a way to draw it out of them, we have to convince them to be willing to draw it out.
Because as the Rambam explains, nothing is external to HaShem, everything we desire from Him we must obtain through convincing, through drawing out.
Similarly, everything we want whether it be material or no, comes from HaShem's depths, from what we might refer to as His mind. Just as we never receive what is actually in our friends' mind, rather what they express through their mouth, so too HaShem's light only reaches us through similar filters and tzimtzumim. (translations)
Our prayers ascend to the heights of His intellect, and attempt to draw out His desire to bestow blessing upon us. Now, because He loves us greatly, he always is arroused to desire that which is best for us, and always replies to our prayers with what is appropriate to our needs.
Both on the way up to His highest intellect, and down back to this world, there are many stages, many filters, many tzimtzumim. On the way up, there are Angels appointed to translate, clothe, and crown our prayers with raiments appropriate to each of these levels, so that our prayers are always in the correct context. On the way down, God's light drips in the smallest of drops, (the most the world can possibly bear) to provide precisely what HaShem would like to bestow upon us, and at each level it is clothed and fleshed out to make it appropriate to our own corporeal context.
One of the metaphors used to describe this process is rain. When the thunder (prayers) reach the clouds (which represent the intellect) it draws out droplets of rain which fall to the earth, enter the ground, get pulled up into a tree, and eventually through nourishing the tree produce fruit.
In the exact same fashion a child, which starts as a mere desire in the father's mind, ends up a new born baby.
The Likkutei Halachot on Tefillin (end of Halachah 4) talks about this same idea as regards the writing of the tefillin. Reb Natan explains that the white klaf (parchment) is the clouds, the intellect, the pure unrefined and unrevealed light. It is only through the black letters that are scrolled with a quill onto the page, that the light is drawn out and channelled.
I never before understood this exactly so. The letters, I knew, were bound together and ordered through the universal light. (the klal) But only now do I begin to see how it is that the parchment represents this universal light, and the letters the channels that draw out and clothe this light in a manner that we can receive.
Beyond this, we know that the Jewish people are the letters of the Torah. We are the channels and the clothes through which the universal light of HaShem is garbed and filtered so that it is palatable to the rest of the physical world.
This is our nature, there is nothing we can do to hide or change this. Every thought, every feeling, every word, every act of ours determines how HaShem's light is revealed down here in this world. We can turn it into something despicable or we can turn it into something sublime, something breathlessly beautiful. The only thing we can't do is run away from this reality.
Jews are Jews and will always be. The divine light within you is shining for anyone who has the eyes to see. The beauty of HaShem's light has the power to eradicate any blemishes we may leave on ourselves or on the world. Teshuvah is the process where we refine ourselves so that this light can shine most clearly, where we recognize that HaShem's light is always creating the world, and that we would like to play a part in it, instead of being an obstacle that makes everyone else's world a little bit darker and dirtier.
[500 years is the distance between each world. May we be zocheh to the next level, the next world; and may we always rise from world to world, a praise and glory to the Holy One blessed be He.]