While the first part of Hoffmann's grand work studied theoretical underpinnings of knowing truth, second part should deal with the difficult task of finding truth in practice. This involves going through questions already dealt in the first book, but from a different perspective. For instance, in the first book we learned to classify ideas according to various criteria, such as their sources and their relations to one another. In the second book, Hoffmann wants to merely how to achieve ideas that can be used for acheiving truth.
Now, an important precondition for achieving truth is to have ideas at all – no ideas, no knowing truth. Furthermore, the primary and in a sense first source of ideas is sensation or experience, which also connects ideas with things. Thus, a precondition for knowing truth, Hoffmann says, is to have reliable experiences of things and especially avoid any possible mistakes in experience, reasons for which Hoffmann goes on to enumerate – we might think we have experienced something, which we haven't actually experienced, our experience of something might be lacking in details etc.
Of these reasons, the most important is the first – some things really are beyond the ken of our experience and cannot thus be justified through experience. We have already seen that the truth of experience itself is something that cannot be experienced, but must be justified through some further arguments. Similarly, we cannot really justify through mere experience that what we experience has just the properties we experience it to have. Thus, a Leibnizian, who denied that external things had any influence on our soul, could not say that the world existed in the manner that our sensations appeared to suggest – and not even that there was any world outside ourselves to speak of.
Furthermore, there are plenty of other things that we cannot directly sense, like future events and infinite collections of things, which prevent us from basing universal propositions on mere experience. In addition, because we cannot observe things that haven't really happened, but might have happened, we cannot draw contrafactual conclusions from mere experiences – e.g. we cannot say on the basis of mere experience that someone would have dies, if she would not have taken a medicine.
A further important question for Hoffmann was to decide what sensations and experiences to choose as basis of further investigation, since clearly one could not consider everything one sensed. Here Hoffmann emphasises the role of experimentation. One should not just go on perceiving things randomly, but e.g. make a preliminary hypothesis and see whether it fits what we perceive. Furthermore, in case of complicated questions one should divide the problem into several subproblems, in order to make it easier to find the important observations. This is not to say, Hoffmann admits, that controlled experiments are the only worthy way to experience and that mere observation is of no consequence. On the contrary, it might well be that such observations reveal some unexpected facts that could not have been discovered through tightly controlled experiments.
Such is Hoffmann's short investigation of the intricacies of experience. Next in the progress of methodology, Hoffmann considers definitions.