It’s hard to know where we stand, so R’ Salanter will give us some insight. Am I good or even righteous perhaps; wrongful or even evil (G-d forbid)? Rambam offers us his litmus test. First off, we’re to know that absolutely “everyone has his merits and culpabilities”, given that we’re all only human. But the difference lies in this: “anyone who has more merits than culpabilities is (considered) righteous, whereas anyone who has more culpabilities than merits is (considered) wicked” (Hilchot Teshuvah Ch. 3).
That’s the calculation you’d need to make in order to know where you stand. But here’s the rub: Rambam goes on to say there that “this calculation isn’t based on the quantity of (your) merits or culpabilities, but rather, on their quality. As there are some merits that ‘outweigh’ many culpabilities” and vice versa. As a consequence “only G-d … can arrive at this calculation”.
R’ Salanter makes the point that only G-d can do that since “it’s clear that many things could affect the magnitude of one’s merits or culpabilities”. That’s the main issue that R’ Salanter addresses in this letter (among other very erudite ones that are beyond our scope here), and he ties it into a point he’d made earlier.
He’d said that there’s one overarching principle in calculating the value of one’s acts, and it comes to this: the easier it is for you to refrain from committing a sin, the greater would be the consequences for your not refraining. On the other hand, the harder it would be for you to observe a mitzvah, the greater would be the reward for your having observed it (see Letter 6).
He then presents us with an example. Suppose you were able to study Torah very well that day for an hour, perhaps because you were clear-headed, and there was nothing else pressing or distracting, and you did indeed study. Your hour of study would do you very well, but you wouldn’t be granted with as much credit as you would if you were indeed pressed for time, other things were tugging at you, and you were distracted all sorts of other ways, and you studied anyway. Your having studied Torah in the latter instance would have been exemplary, and you’d be rewarded accordingly
Conversely we’d add, though R’ Salanter doesn’t cite this, if you were harried that day and distracted by one important and demanding thing after another, and it would have been very difficult for you to take time off to commit a particular sin but you did, that sin would be particularly onerous. You could and should have avoided it, but you went out of your way to commit it anyway. Yet if it was a slow day, and you could easily have committed that same sin, and you did, then while that sin would still have been a mark against you, it would not have left as deep a mark against you as the first instance would have since it was harder to be distracted, and one could almost understand your failing to avoid the sin in that circumstance.
R’ Salanter’s primary point, of course, is that only G-d can know the length and depth of the circumstances that either helped or hindered you; He alone could grasp the full picture. His other point, though, is that you might have set yourself in a position to sin or to do a mitzvah less than optimally, and that few of us are wise enough to know.
What can we do to make sure we don’t stymie ourselves, and that we afford ourselves the greatest chance for spiritual growth? As usual, the best thing we can do is to regularly study Mussar texts, as they warn us against the pitfalls and encourage us to do all we can to better ourselves under every circumstance.