When my dad was a bishop in our ward at church, couples would go to him with their concerns, and whatnot. Some couples would go in having a hard time understanding their spouses constant state of sadness, or depression.  It was often very harmful to their marriage; causing stress, frustration, anger.

My dad once told me how he approached this subject and issue:

He would ask the spouse who was concerned or frustrated, “If your spouse had a broken arm or a broken leg, would you want to help them get all the attention from a doctor, or whatever it took, to help mend what was broken?”
They would respond, saying of course they would get them the help they needed to fix the broken bone, or whatever it may be.

My father would then tell them, “Depression is like a broken mind.”

I heard that story years ago. I remember it, and think of it often.
I feel like that is such a perfect way to explain, even if just a little, how and what depression is.