At first I read a Finnish translation from the 80s and thought it awfully unwieldy and unidiomatic. Well, then I read an English translation (from goodness knows what time period) and I'm willing to cut the Finnedition some slack: it seems that translators of this work weren't really professionals in terms of readability, but were rather interested in translating the original pretty much word for word. This caused some confusion in certain cases, even to the extent that I had to look up the original to see what was the point being made - which kind of made me want to read the original instead. While I could somewhat understand the points being made or at least the points that were supposed to be made, the more important aspects of this work, to wit, a sense of piety, devotion, reverence and awe, were completely lost in translation. After all:
Therefore to the groan of praying through Christ crucified, through whose Blood we are purged from the filth of vice, I indeed first invite the reader, lest perhaps he believes that reading without unction, speculation without devotion, investigation without admiration, circumspection without exultation, industry without piety, knowledge without charity, understanding without humility, study apart from divine grace, gaze apart from divinely inspired wisdom is sufficient for him.
About the work itself. The first thing that strikes the reader of Bonaventure is his adamant adherence to the symbolism of numbers: this work is teeming with sets of 3, 6, 7 and 9! This makes following his train of thought rather tricky because of the superabundance of the sets, but I'll just jot down some of the core ones. First of all, we have the "threefold existence of things, that is in matter, in understanding and in the Eternal Art". Developing this line of thinking further, Bonaventure distinguished between three principle powers of the mind's aspectus: the sensory, the spirit and the mind. The first one pertains to actual seeing, the second one to self-discovery and the third one to beholding divine things. (An interesting point one should make here is that for Bonaventure, things going on in the mind were extra-temporal and extra-spatial: our humans' way of gaining a piece of eternity.) Then, further extrapolating from these, we have the six steps of mind's journey towards God: through something and in that something (so for instance, in "actual seeing", we behold God through vestiges of him and in those vestiges). Furthermore, we have the six powers of the soul: "the sense, the imagination, the reason, the intellect, the intelligence, and the apex of the mind or the spark of synderisis".
(This last bit forms by far the most complicated part in Bonaventure's philosophy: what is the difference between mind, soul and spirit? What's the difference between imagination, reason, intellect and intelligence? What the devil's "the apex of the mind"? What role does "understanding" play, since it is namedropped later on in the text? Well, the bad news is that Bonaventure does not define any of these; he merely drops hints of what he might mean by these throughout the text. And here's what I've figured out: Imagination could be the same as it is for Aquinas, that is, the one that forms our concepts but which are still not verified as the real thing. Reason is probably what allows us to use our intellect and intelligence. Intellect is the understanding of definitions and concepts. Intelligence is the verbalisation of the understanding. Apex of the mind is a complete mystery, but I suppose it's the ability which allows us to think of the mystical? And... frankly, I think "understanding" is just a bad translation making things needlessly complicated. The original uses "intelligentia", for one.)
There are plenty of more of those included in the text, and there's no point for me to reel them all off. But the main idea behind the numerical symbolism is both theological, ideological and aesthetical. Obviously, the aforementioned numbers are important for Christianity, so there's no need to explain that aspect. But ideologically speaking, such convenient figures enable Bonaventure to parse reality better and to come up with justifications for his faith. Lastly, the aesthetical element comes from the fact that "all things are beautiful and in a certain manner delectable; and beauty and delectation are not apart from proportion; and proportion is first in numbers". Since God is, among other things, perfect proportion, it makes sense for Bonaventure to see triads, troikas and triumvirates all over the place.
If one were to sum up the message of this book in a somewhat less frustrating and long-winded fashion, I would say it's about... let's say three things. First and foremost: for Bonaventure, nothing is done by us without the aiding grace of Christ. With his help, we are able to commence our journey towards the great Trinity, and we are able to keep our sins at bay. Without him, we would not have our knowledge or our senses intact (this one makes Bonaventure an advocate of illuminationism). Secondly: the task of the believer is to try to approach the mystery of God by first beginning from small things (that there are lots of things in the world, of varying shapes, colour, height...), then seeing and understanding the concepts behind those things (such as magnitude, multitude, beauty, fullness, order). (Note that the presupposition of God is kept the whole time, and the admiration towards him is increasing as the "pilgrim" moves on.) After that, one seizes the concepts themselves, and deduces from there that God has to be the top dog of every single one of these things (like the first being, most perfect, most actual...). And eventually, one should reach the goal of transferring and transforming the whole "apex of affection" into God... whatever that means.
While these things may seem either obvious or at the very least unimaginative, coming from a medieval Christian, the fascinating thing about this is the sheer scope of admiration Bonaventure had for God and how he wanted to share it with others. If a believer were to follow these steps and accept their (at times rather flimsy) arguments, I have no doubt that they would feel a sense of overwhelming awe towards their Creator. And that's what I love about the Middle Ages: awe and devotion. Desperation wasn't still part of the game, since the Christian truths were pretty much uncontested for a long while. The foundations of faith were unassailable: it was merely the works and mysteries of the Creation that sparked wonder. And at times one can catch a glimpse of these qualities when reading the works of the scholastics and other philosophers/theologians.
But the most important rule while doing so is: don't read them too critically. For their arguments are a cakewalk to demolish. Accept or pretend that you accept their reasoning, and see where that takes you.