Hemingway said this, or some version of it, somewhere across his various writings, and the line has been floating around the wider culture ever since. The standard reading tends to receive it as motivational quotation, the kind of thing that ends up on the walls of CrossFit gyms and on the desks of self-improvement consultants. The implication is that the line is telling the reader to focus on personal growth rather than competing with the people around them.
The standard reading is partly right. The line is, in some real way, redirecting the reader's attention away from external comparison and toward internal comparison. The standard reading is also not paying particularly close attention to what the line is actually doing.
What the line is doing, more specifically, is pointing at two different orientations adults can take toward the question of how they evaluate themselves, and naming one of them as the one that produces what most adults are looking for when they use words like "nobility" or "growth" or "becoming a better person." The other orientation, the one most adults actually default to, produces something different that the wider register has not quite distinguished from the first.
What the two orientations actually are
The first orientation, the one most adults default to without quite registering they are doing it, is comparison with the people around them. The adult moves through the wider environment and, in selected moments throughout the day, registers the various ways the other adults compare to themselves. The other adult is making more money. The other adult has the better-looking partner. The other adult is in better physical shape. The other adult is more accomplished in their professional domain. The various small ongoing comparisons produce, in the adult conducting them, a continuous low-grade ranking of where they sit in the wider social hierarchy.
The ranking is real. The ranking has been the operating system of most adult social cognition for as long as humans have been organizing themselves into groups. The ranking is also, on close examination, almost entirely useless for the question of whether the adult is actually becoming the kind of person they would, in principle, want to become.
The reason the ranking is useless is that the comparison is calibrated to external features rather than to anything connected to the adult's own development. The other adult who is making more money may be miserable. The other adult with the better-looking partner may be in a hollow relationship. The various external features the comparison is calibrated to are not particularly informative about the substantive quality of the underlying lives the comparison is operating on. The comparison is, in some real way, ranking the wrong variable.
The second orientation, the one Hemingway is pointing at, is comparison with one's own former self. The adult is not, in this orientation, asking how they compare to the other adults in the wider environment. The adult is asking, more specifically, how they compare to who they were six months ago, a year ago, five years ago. The comparison is calibrated to a variable the adult actually has direct access to and can meaningfully evaluate.
Why the second comparison is harder
The honest acknowledgment is that the second comparison is considerably harder to conduct than the first. The reasons are worth examining.
The first reason is that the second comparison requires the adult to actually remember who they were six months ago, a year ago, five years ago, with enough accuracy to make the comparison meaningful. The remembering is non-trivial. The apparatus has, by design, been continuously updating its model of who the adult is, in ways that tend to smooth over the differences between the current self and the previous self. The continuous updating is what makes the apparatus functional. The continuous updating is also what makes the comparison with the former self harder to conduct, because the former self is not, in most cases, available for direct inspection.
The second reason is that the comparison with the former self does not produce the small dopamine reward that the comparison with other adults produces. The comparison with other adults, when it goes the way the adult wants, produces a small sense of being ahead. The comparison with the former self, when it goes the way the adult wants, produces a quieter sense of having developed in particular ways across the relevant period. The two are not the same. The wider environment is calibrated to reward the first kind of comparison and to mostly ignore the second.
The third reason is that the comparison with the former self, when conducted honestly, sometimes produces the uncomfortable recognition that the adult has not, in any meaningful sense, developed across the relevant period. The recognition is uncomfortable. The recognition is also the precondition for any actual development. The adult who is willing to honestly register the stagnation is the adult who is in a position to address it. The adult who is not willing to register the stagnation is the one who will continue to stagnate.
What the line is not saying
It is worth being honest about what the line is not saying, because the wider register has tended to absorb it in ways that overextend the underlying claim.
The line is not saying that the adult should be in continuous competition with their own former self. The continuous-competition framing is what the contemporary self-improvement register has done with the line, and the framing produces a particular kind of low-grade ongoing pressure that the original line was not calibrated to produce. The continuous competition produces, in most adults who attempt it, a different version of the same exhaustion that the comparison with other adults produces. The variable has changed. The mechanism is the same.
The line is saying, more specifically,
