We have yet to answer the question of what it really means to be at leisure. We'll get there. Pieper is a German philosopher. This means he's brilliant and I have to work really hard to "connect the dots" of the point he's trying to make. Let's leave this question aside for now because before we can approach it we must first examine the nature of knowledge. (There is a "certain interpretation of the human knowing power" which allows work to be glorified the way that it is today.)
Regarding the "act of knowing," Pieper contrasts the modern interpretation (the Kantian view) with the view of the philosophers of Antiquity (Plato, Aristotle, etc.) and the Scholastics (mainly Thomas Aquinas) of the Middle Ages.
Kant believed that all human knowing is exclusively discursive. It consists essentially in the act of "investigating, articulating, joining, comparing, distinguishing, abstracting, deducing, proving--all of which are so many types and methods of active mental effort." Therefore, knowing is nothing but activity in the form of work.
The ancient and medieval philosophers went a step further. They distinguished the intellect into two parts. One part was the ratio (reason) part of the intellect which is discursive as Kant believed. The second part (which Kant denied) was the simplex intuitus ("simply-looking") part of the intellect. This can be understood as "intellectual vision" or "intuition." (Pieper uses the example of the distinction between simply gazing upon a rose and knowing it and taking it apart, observing, studying it, "possessing" it in a sense.)
The ancients believed all knowing involves both. "The path of discursive reasoning is accompanied and penetrated by the intellectus' untiring vision, which is not active but passive, or better, receptive-a receptively operating power of the intellect." In this sense, the Ancients did not believe that knowing was necessarily always work.
OK, so what's the point of all this talk on the act of knowing? The point is that Kant's philosophy can be credited to the current notion of "intellectual work" and "intellectual worker." Kant believed that even the act of knowing, and doing philosophy, was only true, credible, and genuine if there was effort, labor, or work in it. Anything other than that was suspicious. This is very different from what the Ancients believed and what Christians believe, too. The receptive "intellectual vision" is what allows us to receive grace, or the gift of the Holy Spirit, for example. This doesn't go against our reason, but penetrates it, accompanies it as Thomas Aquinas said. Thus, even philosophy, and the other "liberal arts" are only useful if they are under the realm of work for Kant.
Pieper argues that this notion goes against the very and true nature of philsophy and the liberal arts. What makes them "liberal" or "free" in the first place is that they are done for their own sake and not for utilitarian purposes as Kant would have them. Pieper argues that there is justification for the liberal arts and that they are "necessary for the perfection of the whole human community."
To be continued...