Let’s be honest: humans are lazy with fractions. We like halves and quarters because they’re easy to picture—like splitting a sandwich. But two-thirds? Your brain has to actually work. Imagine a chocolate bar. If I say “I’ll give you two-thirds,” you don’t instantly see it. You have to slice it into three equal rows, then grab two. That’s mental gymnastics for something you should be eating.
And yet, two-thirds is everywhere. Ever notice how a “two-thirds-full” glass of wine looks suspiciously like “I’m going to need another bottle”? That’s because our eyes are liars. Two-thirds is the perfect psychological sweet spot: it feels generous but leaves room for a refill. Restaurants know this. They sell you a “large” soda that’s often two-thirds ice. You’re paying for the illusion of abundance.
