This is my current understanding of how the Chakra works - for both Monks and spellcasters (since apparently one of the NPCs in the Monk quest line considers it the same source):
There is a natural wellspring of aether that circulates through the body. This, collectively, is known as the Chakra. There are points within it - the Chakra points - that are normally closed off in most people (seven, if the MNK quest line is to be believed). Points where the aether is "aspected" for a purpose in the body.
Opening these Chakra allows access to this "aspected" aether to be used in the body much more freely, like overclocking a computer or tuning up a car. Having been opened using residual aether from battlefields, it is possible that these Chakra points also modify or amplify the aether en route to where it is needed. This is what Monks do and why they are able to perform such feats.
Meanwhile, casters just pull from this Chakra wellspring wholesale as a power source for their spells. They take this internal aetheric source to externalize it, bypassing the Chakra points and their purpose entirely. Since this is an external use of an internal aetheric source, this requires concentration and focus to re-purpose the aether into its intended form - usually of a destructive nature. Hence the items needed to focus the spell (gem or book), and the time to draw it out of the body to be utilized (cast time).
There is a natural wellspring of aether that circulates through the body. This, collectively, is known as the Chakra. There are points within it - the Chakra points - that are normally closed off in most people (seven, if the MNK quest line is to be believed). Points where the aether is "aspected" for a purpose in the body.
Opening these Chakra allows access to this "aspected" aether to be used in the body much more freely, like overclocking a computer or tuning up a car. Having been opened using residual aether from battlefields, it is possible that these Chakra points also modify or amplify the aether en route to where it is needed. This is what Monks do and why they are able to perform such feats.
Meanwhile, casters just pull from this Chakra wellspring wholesale as a power source for their spells. They take this internal aetheric source to externalize it, bypassing the Chakra points and their purpose entirely. Since this is an external use of an internal aetheric source, this requires concentration and focus to re-purpose the aether into its intended form - usually of a destructive nature. Hence the items needed to focus the spell (gem or book), and the time to draw it out of the body to be utilized (cast time).
~