You can just never speak about it enough.
The more we talk about it, the more people talk about their experiences, the more we learn, and the more normalised it becomes.
Some 300,000 people in Ireland currently have it and over 500 take their own lives each year because of it.
And yet despite awareness campaigns, despite that fact that we know better now and despite a greater understanding of it, there still sometimes seems to be a taboo surrounding mental illness.
That's why it's refreshing to hear Majella O'Donnell speak frankly again about her own battle with depression.
This week Majella revealed that she rang social services, terrified, because she wasn't coping as a mother to her two children when they were just toddlers.
"I was inside in the toilet with the door locked with a three-year-old banging on it saying 'let me in'," she said.
Because there's been such an outpouring of stories about depression, in the wake of Robin Williams' death and the honesty of Irish personalities such as Marion Keyes and Mary McEvoy, we should possibly be fully tuned in to the range of mental illness.
But we're not, it seems. Perhaps we shouldn't even be using words such as 'taboo' or 'stigma', perhaps using them is adding to or creating that same taboo that we're trying to get rid of.
Thank you Majella for talking so openly and honestly about something so personal. It's nothing but positive that more and more people now feel able to talk about their own experiences with depression.
But we can't fool ourselves into believing that we fully understand what was previously unmentionable.
When it comes to depression, things are never that easy. We need to keep on talking.