How did the first mage discover this? This just feels too... refined for it to have been discovered by chance. Perhaps there was an older race, one of sentient crystals, that taught humans how to do this? Or perhaps a small segment of the population has the innate ability to see and manipulate these energies, and over time developed the basic techniques for spellcasting and energy transference?
Here is a bit more about it to help fill in the gaps:
These energies have been around for as long as the world has existed. In a way, you can say that the energies ARE the world. These energies are the building blocks of the world and all living and non living materials within it. Similar to how the big bang theory works but with a bit of differences, this world was created when a vast amount of the energy gathered into a single position and condensed. Much of the energy took on all forms of properties and became the earth, water, trees, etc. Once the properties of the energy has become set as an object, it stabilizes and keeps that form for a very long time. It will slowly break down and eventually turn back into raw energy but it takes a lot of time. As I said before, every movement, action, or breakdown of an object releases raw energy back into the world. In addition, when the energy becomes an object, excess energy is attracted and absorbed by that object. Living creatures constantly use this excess energy to help peforform all the bodily functions we know, from digestion to regenerating and healing wounds. The more complicated the action, the more energy is expended. Because of this, living creatures barely absorb any excess energy due to the high rate of expenditure. Non living objects do not have this problem and are thus able to store higher amounts of excess raw energy. As I said before, different materials with different properties and composition are able to store various amounts of excess energy.
The energy itself can be seen, so it is common knowlege about its existance. It is very light, wispy, and ethereal. If you are not actively looking for it, it can be hard to notice, but people know it is there. I mentioned before that channeling the energy from an object puts stress on the object. This is true for the person doing the channeling as well. You can feel the tug and pull of the energy as you manipulate it. People discovered magic in my world similar to how people discovered how to create fire in the real world. Someone at some point in time was sitting around board and frustrated about something they wanted and was fiddling around with the energies in a location with a high volume of it, such as near a patch of crystals at the base of a mountain ( If you can see it and feel it, why not? ). While doing this, their mind was probably so focused with the object of thier frustration that they may have hardly noticed at first when the energies around them began pooling and condensing into the object of their frustration. This may seem a bit of a stretch, but over millions of years, someone is bound to do it. From there it is just a matter of further experimentation and more trial and error. Eventually people create schools to teach it. In my example, the object of that person's frustration was probably something small and simple. Larger, more complex objects take more focus and available energy to create. It takes a lot of training to create things like fire, water, and lightning. In addition, the objects created in this manner are far less stable than their naturally occuring counterparts. It is just too difficult for someone to focus on the exact composition of an item enough to have it be as solid and durable as the same object made from naturally occuring materials. This means that something like a sword made from raw magical energy is far less viable than one made by hand. Of course, the more skill and experience the mage has, the better the quality of his creation. Though, more often than not, you are better off just finding a blacksmith. Living creatures are even harder to create from scratch due to the sheer complexity and are all but impossible for someone to consciously create in this manner. Currently, no known person has been known to have created anything "living" from raw magical energies. The natural way of pregnancy is a different matter in which the body is placed into a state of instinctually gathering additional energy to supply and grow the child over a lengthened period of time, similar to how the body would regenerate and heal a wound, basing its information on the material it is attached to.
It is interesting that you mention sentient crystals. While the crystals themselves are not sentient, the very magical energies that make everything up IS. In a way, that is. In its raw form, it is too spread out and fluctuating to ever create a conscious thought. When the energy pools together and condenses into a living creature, it is able to compress the sentience and form an single identity within that creature. When the creature dies and the body breaks back down into raw energy, the sentience and energy flow back into the earth. Many people have different ideas about what happens to the person's memories and personality at this point, but that is a different bit of lore altogether. When the energy forms into a non living object, the sentience never really takes on an identity and instead sits in a dormant state with no memories, feelings, or emotions and are unable to create conscious thought. If a naturally occuring object exists that is normally non living but instead has created a personality, noone has ever found it. (Though now that I write this, it does give me some ideas.)
It may also be worth noting that almost all known matter that was naturally created by these energies, was created at the time of the planet's initial creation process and the first few thousand years afterwards. Natural creation takes a very long time and after the majority of the raw energy was expended in the initial creation process, further natural creation has slowed tremendously.
Hopefully this has answered some of your questions. If you need any more clarification or something just does not make sense, let me know. I love to hear what people think and it helps me to know what areas that I need to expand upon or adjust.
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Lunarea: I do kind of like the idea of using one of those as a conduit for the energy, but the main problem with that, for me, is that those resources are just too abundant. I needed something that could be gathered and traded without being too easy or too difficult to obtain. Crystals still fit the proper mold as they are still fairly easy to locate and mine, but the average person is not just going to step out their front door and just scoop one of high quality right out of the grass (Not normaly, at least). Thank you for the suggestion, though. You never know, I may end up making a highly concentrated liquid form of the raw energy based on your suggestion. Hmm, actually, I may just do that.
Anyway, your original suggestion may work better if the setting is a desert or barren wasteland were water is scarse. Or maybe I am just not thinking of the proper way to utilise it.
On a side note: I am not a usual forum goer, so I am not entirely sure on this, but should I have just edited my last post and added this to it, or is a new reply fine? I ask this, because Lunarea posted while I was typing out my last post and I never noticed it until I was finished ( I am a really slow typer ).