In college and after, i used to talk a lot about "soulless" diversions and professions. If asked to define the notion, I would have said something like this: "Something is soulless to the extent that it detracts from the pursuit of higher things—philosophy, contemplation, and the ordered pursuit of the good." In application, though, the notion of soullessness was more narrowly targeted. Certain things were definitely soulless, because of their decadence or (more often) their materialism. Finance and management consulting, economics and related subjects were all harshly condemned for their lack of "soul".
Lying in bed tonight, trying to fall asleep, I wondered what it meant to be soulless—I wondered whether, despite my best intentions and hopes, I am slowly becoming soulless, simply through the gradual transformation of my character over the past ten years. The question is an echo of one of the great anxieties of the boomer generation—the fear of selling out, of being assimilated by "The Man". But for me "The Man" isn't the concept of authority in general, it's the conversion of the mind into a tool. Soullessness isn't obedience, nor is it cheating oneself out of the spontaneity of individual genius or talent—it's the instrumentalization of the intellect in such a way that the mind's habitual occupation is neither ipsum esse (whether merely esse commune or esse per se subsistens), nor the truth, but the accomplishment of tasks so minute that their ordination can exist in a state of perpetual suspension, without reference to the ultimate good.
One experiences a certain delight in accomplishing tasks. There's the delight of accumulation (a materialist pleasure), and the delight of the imposition of will (Διὸς δ᾽ ἐτελείετο βουλή), but there is also a basic delight in the preoccupation lent to the mind by the process of accomplishment.
Goethe's Mephisto warns that ars longa, vita brevis. It is true, but also in a different way—work draws out and fills time, for better or worse, depending on the occupation. Mann complements and completes this insight: Work that is truly ars fills time in a way that enriches it, slows and suspends it, drawing nearer to the eternity which is the plenitudo perfectionis. But work which occupies the mind without directing it toward a higher end, which truly diverts the soul from its life, work which is too much for its own sake by virtue of being for the sake of who knows what invisible or undirected end—this work leaves time barren, and while it may leave one short of life, it does not fill it.
What is needed for good work is not merely a sense of the dignity of labor or the importance of perfection—what is needed is an orientation from the work one accomplishes to a higher end, not merely material, but transcendental—not simply quantifiable or relative or contextual in its claim to value, but stemming somehow from what is absolute. In the absence of that, I think, soullessness sets in.