It's saying that when someone does something repeatedly, it's not really a mistake anymore; it's just how they usually behave. Imagine if your friend always arrives late when you make plans. At first, you might think it's a mistake, but if they keep doing it every time, it's not really a mistake—it's their usual way of doing things.
In everyday life, we all have certain habits or behaviors that we repeat. These actions become part of who we are. So, if someone keeps doing the same thing over and over, it's not by accident; it's their regular pattern of behavior.
In essence, this quote reminds us that when people consistently act in a certain way, it's not a one-time error but a reflection of their character and habits. It's like saying actions speak louder than words, and what we do repeatedly defines us more than occasional slip-ups.