I am 43 now, but I can still remember very clearly learning about guns as a teenager. I began ignorant and afraid, but learning about firearms, learning rules for safe handling and cleaning, learning range safety, etc. removed that fear. It has always been an interesting experience for me ever since to go to a gun range with someone unfamiliar with firearms, and to see their attitude change with knowledge and familiarity.
Magic is not a plague, any more than steel and gunpowder are plagues. It is a tool which, like almost any tool, can be used to create, destroy, fix, or break. Like a firearm, it will hurt you or someone else if you use it carelessly. It is dangerous if you don't respect it. To be safe, you need to know what you're doing and do it right.
Fear comes from ignorance. In Thedas, too often ignorance comes from the Chantry.
Age really doesn't have much to do with this Debate, but i can point out i am past the age of thirty if we are doing a comparison
And comparing firearms to magic while not entirely inaccurate is willfully leaving out how that comparison doesn't cover the parallel very well. I can if i so choose ultimately put down my firearm, I can if i so choose ultimately not use one. Magic is always there within Dragon Age, its a thing that seeps into the very blood if allowed. It festers within the Mage until they become a danger to themselves or others, This isn't always the case; with proper training they can even be useful.
But they are still a danger, Not only due to the failure of personal will and ego but also because of the beings that lurk beyond the veil.
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Magic is a tool, but it is also a curse, it attracts ethereal beings that seek to subvert Human will and turn humans into quite literal abominations.
What sort would i be if i didn't seek to prevent that? to want to protect the common man from such beings? That is why magic must be confined, that is why magic must be controlled and that is why mages must never be free. You allow the temptation, the thought of freedom and it drives them to madness, Subverting the will of their common man couldn't be anymore encouraged then possession, its no more then containing a threat.
And You leave out that Fear is a legitimate and useful response to things that cannot be controlled and that are dangerous.
And the Chantry even if the Dogma is false, isn't wrong about the threat of magic and isn't wrong about it needing to be sealed away from the normal people.