"Wow, this guy really knows what he's doing!"
This is a perfectly natural, expected reaction when listening to an accomplished cellist, a potter at the wheel, a smith at the forge or any master craftsman at work as our plasterer depicted here. What the aforementioned all share in common is that they all make an extremely complex activity appear almost effortless. Their demonstration of competence commands immediate respect. We acknowledge that such mastery takes inner discipline, a substantial commitment of time as well as the accumulation of a fair bit of knowledge. Whereas English has only a few related terms, many other languages parse what we call "knowledge" into a number of nuanced meanings. In the process leading to mastery we can think of these manifestations of knowledge as incremental stages of development.
Second-hand, Given Knowledge
The Ancient Greeks placed the least amount of value on second-hand knowledge, doxa that is often translated as mere opinion. In its simplest form doxa may be nothing more than a narrative that we receive; that is to say, we "know" something because we heard about it. It's not the case that we've directly worked it out for ourselves or personally have done something. Rather, it consists in nothing more than a belief in or acceptance of something because it originates from an source in which we place trust. Closely related to doxa is the Latin term pistis, an intellectual and emotional acceptance of a proposition often translated as "faith" whereas doctrina referred to the articles or literal contents of faith (catechism) as taught by the Catholic Church. To "indoctrinate" maintains this negative connotation of the insertion of knowledge into an ostensibly intellectually empty human vessel.
In our more honest moments, I think we must confess that we depend upon this type of second- hand knowledge quite a lot. For example, whenever we read or listen to the news, accept reports regarding climate change from scientists or receive medical advice from our doctor, all of these reports represent doxa, forms of second-hand knowledge. The trouble arises because it's really easy to claim to know in a profound sense what in reality we've merely read or heard. In such cases what we're really doing is expressing a belief commitment. In our defence, there are tremendous constraints on how much we can personally learn and experience. We cope with this by outsourcing the problem socially and as long as our sources have real knowledge (are not mistaken) and are not trying to deceive or manipulate us it can be quite helpful, even necessary. However, we ought to be instinctively cautious of second-hand knowledge as mistakes, deceit or even our own misinterpretation tend to creep in and lead to paradox, literally "contrary opinions".
There are a number of ways in which craftsman can acquire this kind of second-hand knowledge. We can certainly learn a few things about a given craft by reading about it. Likewise we can discuss it, having an experienced craftsman explain various aspects of the craft. Nevertheless, as craft is primarily experiential as opposed to being understood intellectually, literal and verbal explanations provide at best partial or low image resolutions of craft. Watching a craftsman at work or demonstrating his craft can add further insights whereas physically viewing, touching and measuring a completed work may yield a better understanding. Nevertheless, none of the aforementioned hold a candle to directly engaging in craft yourself.
First-hand, Acquired Knowledge
Two forms of acquired knowledge are necessary for craft. Both of these must be acquired directly yet are very different in nature from one another. Let's first address Theory. The Greek word from which our English word theory derives, theōria, literally means a kind of disinterested contemplation as a spectator may hold of a performance at a theatre. Just as there is no necessity or end goal of a performance, theory is a kind of knowledge for its own sake and pleasure. In Enlightenment language we might say that this species of knowledge is a relation of ideas held in the mind. The process of establishing truth claims built upon initial axiomatic presuppositions was known as analysis by the Greeks and scientia by the Romans. Both of these terms conveyed the concept of cutting apart mental constructs so as to reassemble them into ordered wholes. Geometry, deductive logic and arithmetic would be examples of such theoretical knowledge characterised by timelessness, universality and formality whilst being immaterial, that is to say creating no product nor engaging an action. Epistemology is one of the three main branches of Western philosophy that concerns itself with what constitutes knowledge. The Greek word episteme literally means to "stand over", implying a type of knowledge that stands removed, detached from the object or action of contemplation.
As craftsman we learn abstract systems of proportion and conventions when working inside of a given tradition. As a preeminent example, Classical architecture since at least the time of Imperial Rome has documented these systems into "canons", theoretical standardisations of its three principle orders, that is to say styles of building: the Doric, Ionic and Corinthian. Likewise, other architectural traditions such as Islamic, Vedic, Gothic, etc. possess their own conventional systems whose theoretical knowledge was retained and passed on through various iterations of trade guilds and apprenticeship programmes. Design is initiated from a theoretical point of origin and extended into three dimensions as represented by line, surface and enclosing volume. The elements, that is to say the smallest components of an assemblage, are all derived from fundamental geometric principles such as the circle and the square as well as the various conic sections: ellipse, hyperbole and parabola. A master craftsman (technitês) must be able to perceive, literally "thoroughly grasp" (Latin percipere), such theoretical principles.
A second form of personally acquired knowledge necessary for craft is of course Practise. Our English word derives from the Greek praktikos meaning "to do" or "to act". Practical knowledge is contingent upon what the Greeks called a telos: a goal or function inherent to a made object. Unlike theory, practice is inductively applied particular knowledge of matters of fact to fulfill some specific need or desire. It is thus an interested form of knowledge tied directly to material and action, a knowledge for something's sake as it were. Rather than any universal truth, practical knowledge seeks an arete, an excellence of value in the action or object made. Of interest the very word "philosophy" originally meant a "loving", philo of "skill in handicraft and art", sophos as characterised by its use in Homeric poetry of ancient Greece before its meaning was extended to include a love of wisdom in a more abstract and general sense.
This kind of practical "know how" was best captured in the Greek word techne, the Latin word artes carrying a similar meaning. Philosophers such as Socrates, Plato and Aristotle denigrated most craftsmen as mere banausikai techne, illiberal servants whose works were self-centered, of questionable merit and unbefitting of a gentleman. Aristotle in particular expressed that value rested only in the crafted object, not in the means of bringing the object into existence. This is a view that persists in contemporary times when far more value is placed on the end product and little concern given as to how that product is brought into existence. More often than not the process, tradition or training infrastructure required for skilled craftsmanship are ignored in favour of a dogged focus on bottom line price and schedule. By contrast, many Stoics held a more charitable view of skilled craft according value to practical experience, phronêsis as a virtue unto itself. All agreed that a master craftsman was identified by his sapientia, his ability to teach, furnishing a verbal or written account of the craft itself whereas a chief craftsman, architektôn further distinguished himself by his mastery of theory and practise combined with an ability to command others.
In my own experience of teaching traditional plasterwork, the first thing I do is disabuse the students of the notion that I can teach them much at all. Like all traditional crafts, plastering is an embodied form of knowledge. Apprentices have to teach themselves or perhaps another way of stating it, they must unlock their already present potential to plaster thru repetitive action...craft as a form of ritual. I certainly can't plaster for the students; the most I can do is say a few words in the form of encouragement or critique and demonstrate actions whilst they observe. Learning a craft is more akin to a remembrance, the awakening of a capacity already present in the individual. The role of a master is less of a teacher as it is that of a spiritual guide. This type of knowledge has been described as empeiria, that is to say empirical knowledge. Unlike the aforementioned forms of acquired knowledge episteme which can furnish a verbal or literal account, empirical knowledge is internal, non-discursive and straightforwardly acted out.
The ancient Greeks had a specific word for this kind of knowledge, gnosis. As you may already suspect this is the origin for our own English words "to know" and "knowledge". The sense of gnosis is quite intimate, more of a "knowing who" than a knowing how or what. It is the type of knowledge you'd have of a dearest friend or loved one. It's not a collection of facts about them, rather a deep connection that is shared.
To become an effective craftsman you must lose your mind. In the process of learning the student initially attempts to think thru and control his movements, ultimately a futile effort that leads to complete exhaustion. The student understandably wishes to know what to do in the sense of being informed of the correct materials, means and methods. Although there is a place for that, it is secondary in the learning process as information is always particular and soon becomes redundant. By abandoning oneself to the ritual of craft the student is rather transformed and an insight grows spontaneously from visceral, direct, embodied experience. For the master craftsman, knowledge sublimates into action, his knowing is making.