It was evident that a similar analysis might have been applied to tactual consciousness which does not give externality in its deepest significance any more than the visual; but with deliberate purpose Berkeley at first drew out only one side of his argument.
The battle of his life was on behalf of personal religious experience, in opposition to the externality of rationalism, orthodoxy or sacramentarianism.
This externality of religious truth to the mind is fundamental in scholasticism, while the opposite view is equally fundamental in mysticism.
In the Principles of Human Knowledge, externality in its ultimate sense as independence of all mind is considered.
In these works he attacked the existing theories of externality which to the unphilosophical mind is proved by visual evidence.