In some schools, there is this talk of omote (superficial techniques taught to anyone) and ura (deep, hidden teachings only taught to the initiated) but Musashi in the end of the Wind Book writes about there being no internal teachings and no gate:
There is no "interior" nor "surface" in strategy.
The artistic accomplishments usually claim inner meaning and secret tradition, and "interior" and "gate", but in combat there is no such thing as fighting on the surface, or cutting with the interior. When I teach my Way, I first teach by training in techniques which are easy for the pupil to understand, a doctrine which is easy
to understand. I gradually endeavour to explain the deep principle, points which it is hardly possible to comprehend, according to the pupil's progress. In any event, because the way to understanding is through experience, I do not speak of "interior" and "gate".
...Accordingly I dislike passing on my Way through written pledges and regulations. Perceiving the ability of my pupils, I teach the direct Way, remove the bad influence of other schools, and gradually introduce them to the true Way of the warrior. The method of teaching my strategy is with a trustworthy spirit. You must train diligently.
…In my Ichi school of the long sword there is neither gate nor interior. There is no inner meaning in sword attitudes. You must simply keep your spirit true to realize the virtue of strategy.
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