Like the logic textbooks of the time often did, the final few chapters of the work of Crusius treat the question how to apply everything previously said to the practices of scholarly work. Crusius speaks more precisely of meditation, by which he means a process of extending our knowledge further from some fundamental thoughts. In addition, he considers also the related problematic of how to transmit the internal meditation to others in a scholarly treatise, which requires accommodating the results of meditation to their needs. Crusius also ponders the practices of disputation, but has not that much new and interesting to say about the topic, so we’ll ignore it.
Quite traditionally, Crusius distinguishes two different types of meditation: analysis, where we try to make our knowledge of the fundamental thoughts more distinct, complete and certain, and synthesis, where we progress from fundamental thoughts to other truths that are not its part nor grounds, but are merely inferred from it. He notes that both actual meditation and scholarly treatises use both methods and that sometimes even individual pages in treatises can have many occasions of both methods.
In the synthetical method, Crusius thinks, the fundamental thoughts studied must always be concepts, but the analytical method can also have as its object words, the meaning of which is sought out. Thus, he argues, the analytical method is divided into analysis of things or concepts and analysis of words or terms. Starting with the analysis of concepts, Crusius divides it again into analysis of parts, which sets out distinctly all the parts and internal determinations of the fundamental thoughts, and analysis of reasons, which looks for proofs for the fundamental thoughts and evaluates proofs suggested by others. The difference of the latter from the synthetical method, he explains, is that we are usually convinced of the proof of the fundamental thoughts and we just want to make this conviction more secure.
Crusius divides the analysis of parts again into merely resolving analysis, which sets apart distinctly just what is already in the fundamental thought, and determining analysis, which adds further determinations to what is still indeterminate in the fundamental thought. He calls the latter also mixed analysis, because it often has to use also the synthetical method, although for an analytical purpose. This determining or mixed analysis, Crusius explains, adds either determinations that belong to the object all the time and thus are part of its essence or determinations that belong to the object disjunctively through divisions.
Crusius notes that the methods of analysis of parts and analysis of reasons can also be combined. This combined method is especially used, he explains, with problems, where we start from given data and progress to the grounds, on which the data depends, and generate from the characteristic or quantity of the grounds the required characteristic or quantity. In this method, Crucius points out, the first move toward grounds is analysis of reasons, while using the grounds to make the previously unknown determination distinct is determining analysis. He points out that this method is especially used in mathematics, under the name of algebraic method, when we are asked for a magnitude of something and we determine it through other magnitudes, on which the first one depends.
Analysis of words or texts Crusius divides into three types. Firstly, it may be about interpreting a text, it may be about outlining the order or disposition of the text or it may be about evaluating the worth of the text. The interpretation is something Crusius will return to in the final chapter of the book, so he in this point merely divides disposition of text into natural disposition, which follows the goal of the author, and artificial disposition, which follows any convenient general concept, and divides evaluation of the text into evaluation of the writing style and into evaluation of the thoughts in it.
Crusius lists three kinds of synthetical method, which he names after the sciences prominently using them. First of them is the geometric or mathematical method, which takes as its starting point the concept of a possible essence. The second, then, is the physical or experimental method, which starts from propositions involving physical existence. The final one is the moral method, which begins with propositions involving moral existence. Crusius notes that the physical and the moral method together can be called the philosophical method.
Crusius goes through the different types of synthetical method in more detail, starting with the mathematical or geometrical method, where the possible essence it begins with is such that the existence of which is not yet posited or at least not yet considered. This method then proceeds to find out more about the relations and consequences of the essence and discusses problems following from these. Crusius notes that the specialty of the geometrical method is that it does not prove its definitions, but just postulates them as possible. Thus, he argues, propositions shown by it have only a hypothetical reality, which is enough for pure mathematics. Then again, Crusius points out, the geometrical method is used elsewhere, for instance, in studying the relations of possible essences.
The physical method, Crusius continues, starts from experiences or real propositions deduced from experiences – he notes that all existences must in the end be justified from experiences. The method then proceeds to other propositions involving physical existence or real possibilities. In other words, Crusius explains, the physical method moves from effects and properties of things, known by experience, to their causes, further effects and relations. The method is used, naturally, in physics and also in medicine, which Crusius takes to be a special subspecies of physics. He notes that this method is used also elsewhere, for instance, in revealed theology, where the Bible takes the place of experiences.
Moral method, finally, proceeds from fundamental thoughts to the purposes of things or from posited purposes to other purposes, whether these purposes concern human happiness or moral laws. In case of moral laws, Crusius thinks that we know them sometimes through sensation – when we are speaking of written or announced laws – and if we are speaking of natural laws, we can know them by deducing from experience, although he warns the reader not to confuse inferences from what makes us happy for a proof of moral law. Crusius also points out that studies of moral existence or possibility should not be confused with studies of efficient causes and means that make certain conditions of mind possible or actual, because the latter demand the physical method. Then again, he adds, most moral topics also require these physical investigations.
Crusius states that the synthetical method cannot be applied before the fundamental thoughts are distinct and known to be real or at least possible, which presupposes that we know definitions, experiences and other propositions. Definitions in particular, he says, should at least be resolved into axioms, and if this is not enough, determining analysis is required. Thus, Crusius argues, both analysis and synthesis are required in meditation, but synthesis presupposes analysis. Furthermore, he continues, each thing must be studied according to its nature. For instance, existence must be studied analytically and especially through determining analysis or synthetically with physical or moral method or often by both means, while study of essence requires mathematical method or analysis.
Crusius also gives some general guidelines on how to go about in meditation of things. A central concept here is the theme of meditation, by which he means its main or objective purpose. The theme is either simple – a concept, a proposition or a problem – or composed of many simple themes. If the theme is something arbitrarily made by humans, Crusius says, we should check whether it is useful to investigate it. With naturally generated things this check is not required, he thinks, because knowledge of such things enriches the sciences and influences many truths.
In order that meditation will be useful, Crusius explains, we should already have some capacities for meditation, which requires a diligent and thorough study of logic. In addition, he notes, meditation requires materials, which are supplied by preliminary knowledge that helps to form concrete ideas, both on the general structure of all sciences and particularly on sciences close to the theme investigated. Crusius also instructs the reader to learn about history, because historical knowledge can provide experiences and understanding on causes of many possibilities.
After gathering this preliminary knowledge, Crusius explains, the meditation starts by directing attention to the fundamental thoughts and trying to think them lively and ever more perfectly. This means, he adds, reflecting on and analysing examples that fit the concrete ideas, together with the opposites of these examples and the predicates that are ascribed to the examples through the concrete ideas. In addition, we should recollect what we have heard and read about the topic and perhaps collect more experiences about it. When all of this is done, Crusius suggests, we should draw an outline of the meditation to guide our imagination, by determining the main points in the theme, to which meditation should be directed.
Once we have fixed the purpose of meditation, Crusius insists, we should make a special theme about the requirements of the method. This means, firstly, he explains, planning a good order for the meditation or the treatise made through it. The general rule, Crusius says, is to start with that without which the following cannot be understood, at least not as conveniently. This does not mean, he clarifies, that nature would determine the place for each thought so precisely that they could not change their places, because there’s much arbitrary in the order of meditation and scholarly treatises.
Something peculiar to treatises, in opposition to meditation, Crusius suggests, is that although in meditation scholars should be ready to reduce everything to first grounds of all sciences, it would be too difficult to do that for every proposition and often superfluous in the eyes of the reader. Still, he adds, we should not assume as familiar what is doubtful and we should try to find justifications even for familiar truths, especially if this is a key to finding desired truths, or to shying away from difficulties.
Crusius suggests that the working of themes is easier, when their main points are classified and ordered under a few titles – he calls this classification by the Aristotelian term topics. I shall skip this part of the chapter, because it consists mostly of titles of the treatise to be made.
