There is a message inside of There’s a Ghost in the Garden by Kyo Maclear, but it is one that will be different for each reader. Also, it is okay if you just enjoy the words of Maclear, the flow of text and the illustrations (by Katty Maurey) without taking any meaning from them. It works on both levels allowing the reader to take what is needed at each listen and/or reading. This can work for many ages, though it is for slightly older listeners/readers. 
The flow of things represents a river, such as the river in the grandfather’s memories. The text not only reflects that but so do the illustrations. They are not just simple illustrations, but art that captures the dreamy, ghost-like atmosphere of things. Yet, everything fits together well. The idea of “ghosts” can be literal or emotional. At first I thought there was the ghost of a grandmother figure, but then there is the ghost of the past and the youth of the grandfather. It is up to the reader to interpret whether things are “real” or imaginary. I really cannot say a lot about things, as it was an emotional reaction I had. I felt the book more than heard it.
Due mid/late October 2025 this online reader is a book that I plan on finding the physical copy of to give to the library. It could be a book you use for when a beloved family member or friend has passed, but it also is just a book about time. And in that way you can just share it with the child/children in your life. I think it would work best with one-on-one reading and not a large group (two or three might be okay).