Mystics have known this truth throughout the ages. Granted, the carvings of sorrow are not so much the fun part. It could be losing a loved one, a serious illness or accident, or betrayal. It can also be "day-to-day sorrows." Here's my example. Yesterday, with my husband away for a skiing break, I took Barney to work with me at the tax office. We are becoming quite busy now, with many folks dropping off their tax documents and picking up completed returns. Every time another person approached the door, Barney started barking, his innate doggie behavior. He's not mean or dangerous. He wants to play.
Barney's mom, me, on the other hand, soon got to the point where each bark felt like someone sticking a screwdriver into my brain. This is not a good place to be for tax work. We left early, with me exceedingly irritated with Barney, which creates a state of sorrow in me, because I dearly love him. We went on another walk, it being a lovely spring-like day, and he finally settled down. He is well aware of my not-pleased glare. Despite my irritation, I melt every time I look at him. He is a source of enormous joy, and I can't imagine life without him.
Sorrow and joy go together like peanut butter and chocolate.