[SoboSobo]

Originally Posted by Echizen777

He has a tendency to overestimate Tatsuya and his abilities but he need ES, if he can' identify the target(Parade) or if the target has no form in the ID, it won't work.

i might go a little overboard about his abilities, i admit that. But i`m not over estimating him.

Originally Posted by Guest2

The novel explained in V2c10 all magicians have a sensory ability they use to identify eidos and that Tatsuya's ES is just better version of this. Decomposition of eidos doesn't require someone who has ES. The novel explained in v2c11 ES is only necessary for decomposing information bodies like magic and activation sequences, non-systematic decomposition magic.

Spoiler for volume 2 ch 10:

All users of modern magic could access the information dimension — the information medium of the universe, the platform that linked all eidos, as defined in the Greek philosophical concept of "information" — in order to identify other eidos.

That being said, very few people could clearly identify and differentiate them.

What radically separated Tatsuya from ordinary magic users was his incredible aptitude in sensory ability, to the point that he could identify each and every eidos encompassed in the information dimension.

Normal magicians can identify the eidos as a whole. As an example in a class room the normal magician can identify the eidos in the room but they can't tell which eidos belongs to the chair and which eidos belongs to the dashboard or to the computer.This is where tatsuya ES comes in it gives him the ability to differentiate and identify every eidos individually meaning he can tell which eidos belongs to the chair, the computer etc. And that's why he needs ES for decomposition in order to individually target the eidos he wants to decompose otherwise he will just decompose everything.