The next question to consider is: What are the limitations on what magic can do?
Limitiations of Magic
The greatest limitation is simply that of available energy. The laws of physics remain intact: a magician must provide an equivalent (and nearly always greater) amount of energy to accomplish any given effect then would be required by non-magical means. When in doubt, pick up a physics book and work out an idea of the amount of energy needed to do the basic operation (move a rock, ignite something) and try to compare it to real life to get an idea of the effort required.
The next greatest limitation is the caster’s knowledge and imagination. It is not necessary for the magician to know absolutely every detail of the effect that they want, but the more detailed their knowledge (or imagination), the closer to “correct” their effects will be.
A prime example is healing. The average magician will simply not know enough about the workings of the body to be able to produce a meaningful, beneficial effect. The level of detail of the knowledge required to heal someone properly is simply not available, and imagination is not sufficient when tampering with a living body. Gods with their expanded knowledge can produce the necessary detail. Therefore, priests and witches can accomplish healing effects that are completely lost to magicians that rely on their own devices.
Another excellent example is the creation of items purely through magic. A magician needs to know every intimate detail of the item they wish to create in order to produce it properly. If a magician creates a sword only knowing that it is a sharp piece of iron of a specific shape, they will get a nearly useless sword-shaped piece of raw pure iron. Knowing that carbon needs to be mixed to make it into steel helps, but they must know the proper proportions. They must understand the effects of forging and tempering to reproduce those as well. And unless they are familiar with engraving and have a decent artistic capability, their decorations are unlikely to be aesthetically pleasing. All in all, only a magician who happened to also be a master sword smith could create a reasonable sword through magic (and even then, the amount of magical energy needed would be enormous). Food is even worse. It is easy enough to make something look like a very plain, undecorated cake. Decorations must be looked after. And they must not forget the various flavors of the cake itself, the filling between any layers, the various frostings, and so on. And the myriad textures – the soft cake, the creamy frosting, the slightly hardened sugar decorations… Once again, only an accomplished baker could create a cake by magic, and it would likely be far too expensive in terms of power to be worth the trouble.
In summary: direct simple effects, or effects that can “make do” with limited correlation to non-magical effects, or effects that have no non-magical counterpart are easy enough. The closer that a magic result needs to match a similar non-magic result, the more difficult the magic is to perform and the more specific the knowledge that is required of the caster.
There are otherwise no strict artificial limitations on what can and cannot be done. The basic limitations combined with the nature of the energies used are sufficient. Psychic energy can be used to read someone else’s mind, unless they are shielding, but you might be able to overcome their shielding – and so on.