The respected New Yorker staff writer George Packer captured this fear well in an essay about why he does not tweet: “Twitter is crack for media addicts. It scares me, not because I’m morally superior to it, but because I don’t think I could handle it. I’m afraid I’d end up letting my son go hungry.

the bimodal philosophy of deep work. This philosophy asks that you divide your time, dedicating some clearly defined stretches to deep pursuits and leaving the rest open to everything else. During the deep time, the bimodal worker will act monastically — seeking intense and uninterrupted concentration. During the shallow time, such focus is not prioritized.

Ironically, jobs are actually easier to enjoy than free time, because like flow activities they have built-in goals, feedback rules, and challenges, all of which encourage one to become involved in one’s work, to concentrate and lose oneself in it. Free time, on the other hand, is unstructured, and requires much greater effort to be shaped into something that can be enjoyed.

This magician’s trick of shifting the units of measure from money to time is the core novelty of what the philosopher Frédéric Gros calls Thoreau’s “new economics,” a theory that builds on the following axiom, which Thoreau establishes early in Walden: “The cost of a thing is the amount of what I will call life which is required to be exchanged for it, immediately or in the long run.

In Lynn White Jr.’s study of the stirrup we find a classic example of a technology introduced for a simple reason (to make riding horses easier) leading to vast and complicated consequences never imagined by its inventors (the rise of medieval feudalism). In the second half of the twentieth century, many scholars in the field of the philosophy of technology began to research similar case studies of unintended consequences. Over time, this idea that tools can sometimes drive human behavior became known as technological determinism.

Deep work should be a priority in today’s business climate. But it’s not. I’ve just summarized various explanations for this paradox. Among them are the realities that deep work is hard and shallow work is easier, that in the absence of clear goals for your job, the visible busyness that surrounds shallow work becomes self-preserving, and that our culture has developed a belief that if a behavior relates to “the Internet,” then it’s good — regardless of its impact on our ability to produce valuable things. All of these trends are enabled by the difficulty of directly measuring the value of depth or the cost of ignoring it.

He asks us to treat the minutes of our life as a concrete and valuable substance — arguably the most valuable substance we possess — and to always reckon with how much of this life we trade for the various activities we allow to claim our time.