Synopsis of previous section:
Hisbonenus is essentially the idea of looking intensely into the depths of a topic and going over it a lot until one understands it clearly with all its parts in particular detail. And this is the innerness of Binah (understanding) which is called in the language of the Talmud Iyun as it says in Tractate Succah "there's a type of study called Girsah (fast superficial study) and a type called Iyun (deep intensive study).
The explanation of Girsah is to just understand the topic at first glance which passes and flows rapidly (from point to point) without any stopping to go over the subject matter.
The Mitler Rebbe will now proceed to explain the mechanics of the mind in Kabbalistic terms:
For every concept possess three dimensions: depth, length and width.
The width of a concept is the explanation of a concept to every side, with many details, like the width of a river; and not merely saying it like it is without explanation, like a narrow river. The same is true in modern terminology. For example, when we speak of a broad subject, we mean that it extends or finds application in many fields, encompasses many diverse ideas, or has many different explanation. Similarly when we describe someone as possessing a broad knowledge, we mean that his knowledge extends to many different areas and is not limited to just a few subjects. This does not however indicate that he has a great proficiency in these subjects, nor that he can explain them, only that his knowledge encompasses many different facts. So too, when we speak of the width of a concept we are discussing the number of different kinds of details or examples it contains, or in how many ways it can be explained. This is like a wide river that covers a lot of area at each point along its length, and can be divided into many individual streams of water. For example, a subject like mathematics is very wide for it encompasses many specific subjects like addition, subtraction, whole numbers, fractions, algebra, calculus, etc. and each of these in turn includes an infinite number of specific problems. Therefore its explanation is very wide with a lot of details and takes years to learn. The rules of football, on the other hand, is a much narrower subject and doesn't take so long to learn, for it has fewer details.
The length of a subject is the intense descent of the mind necessary to enclothe a concept into various analogies, until the concept is brought within the grasp of even a small child etc. Like a river that flows forward extending over a great length. So that, just like a river flows downward carrying water from high in the mountains to low lying valleys and plains and the higher the mountain the longer its descent; so too the length of an idea is the measure of the amount of simplification needed to make a concept easy to understand.
Some concepts are very simple and can be readily understood by even a small child, while others are very far from the grasp of a child being naturally lofty and theoretical and so it is more difficult to explain simply. The "distance" between the natural understanding of the concept and the understanding of a child is the length of the concept.
(As is explained at length in the Chassidic manuscripts on the subject of the length of the skins used to cover the Tabernacle. What it basically explains there is that length implies one thing that undergoes many changes, yet retains its identity. For example, a long trip passes through a lot of different scenery and many stops on the way, but it all is really for one purpose, to move from point A to point B. All of the points in the middle don't change the theme of the trip, they only make it longer. Similarly when we say that an invention has come a long way, such as the development of the airplane since the Wright brothers' historical flight, we mean to say that it has developed tremendously, changing drastically. Yet, we can only say this about something that remains essentially the same. Like the airplane, whose basic concept has not changed, it is still a flying machine with wings. On the other hand we would not usually describe the development of the airplane from the bicycle as having come a long way, even though the Wright brothers used their knowledge of bicycles to help design their plane, because it is not one thing, the entire essence changed. So that just like physically we only describe something as long when remains essentially the same thing while undergoing many changes, so too a concept is described as long if is explained in a very different simpler way while remaining essentially the same. So that if Einstein were to explain his theory to a small child we could say that the theory went a long way from the understanding of Einstein to that of the child.)
The depth of a concept is like the depth of a river, that from there it widens out, but it itself is not wide at all. This depth (which is called the undercurrent) is the most essential part of the river for it is the main flow of water from its source. The essential defining factor that distinguishes a river from other bodies of water such as, for example, a lake, is the fact that it is a moving body of water, flowing from a mountain to the ocean. The usual way that a river is made up is that the water on the sides tend to be shallow and calm, while in the middle the water is deep and flows quickly, freed from the friction with the sides. This quick current is often unapparent from the surface and at times is so strong that it can be potentially dangerous to swimmers, at times sucking an unwary swimmer under with it or just carrying him quickly down stream. This hidden power is made apparent only when its flow is obstructed by something, giving rise to great rapids.
Similarly, the depth of an idea is the essential point of the idea, as it is essentially, transcending explanation or definition. This is also what is called the Omek Hamusag (depth of the understandable, or more literally the depth of what can be grasped.) This is when one understands an explanation so that they actually get the point of it, that which was not actually explained. It is from this inner point that everything spreads out from, forming the many explanations of one's understanding to all sides, with a great width, encompassing many details.
For example, when one learns how to add in school, the teacher gives a few examples on the board and shows, step by step, how they are solved. Then the teacher gives the students different problems for homework, ones that were not explained before. But how are the students supposed to solve them if they were never explained before? The answer is that after the students were explained a few examples they get the hang of how it’s done. This was the real point or depth of the explanations, so that they can add any problem, not just the ones they were given. So that once one knows how to add in the way of a point - in a way that ‘you just do it,’ then one can add any problem. Then one's understanding will automatically encompasses the width, of how to add all of the specific problems, as well. So too the length of an idea, with the intense descent of the idea to be enclothed in examples and analogies. This too comes out of the original depth and was included within it. Like when a teacher teaches young children how to add, even beginning with 1 + 1 = 2 is too abstract and must be lowered into a more physical example, like one apple plus one apple is two apples. Now the inner theory of mathematics can really be applied to add anything and the knowledge of adding apples was included in the inner understanding of how to add and once one learns how to add then one can add anything.