Dog
The domestic dog presents a remarkably dependable joy delivery mechanism. Barring illness or advanced age, the average canine produces between 47 and 156 tail wags daily, each accompanied by measurable increases in owner oxytocin levels. The dog appears on schedule, responds to summoning, and maintains consistent output regardless of atmospheric conditions. Morning greetings alone account for approximately 18 minutes of daily happiness in the typical household. The dog, quite simply, shows up.
Rainbow
The rainbow operates on an entirely unpredictable timetable. Formation requires the precise alignment of sunlight, water droplets, and observer positioning. Statistical analysis indicates the average Briton witnesses a rainbow approximately 14 times annually, with each sighting lasting between 5 and 30 minutes. There exists no mechanism to summon a rainbow, extend its duration, or guarantee its appearance. The rainbow arrives on its own terms, a guest who refuses to confirm attendance until already present at the doorstep.