For my birthday, we got to go to Lyndhurst Castle in Tarrytown NY, right next to Sleepy Hallow NY. The castle was cool, but my center of focus was their Bouguereau collection. They have another Bouguereau on display, an earlier work from 1866 titled "First Caress", but I want to focus on this Madonna scene.
The main thing that stood out to me in this was how he left some impasto brushwork on the child's feet (which you can see in the photo) and also how the ebauche is left in the foliage. Some people suspect that Bouguereau scraped his paintings smooth, but I disagree with this. There's actually quite a bit of brushwork left visible. It looks very smooth in the photograph, but it looks very different in person. The painting was clearly built up with a series of scumbles, leading to some fairly thick paint in certain areas. It's hard to describe how Bouguereau achieves this unfinished/finished effect, but it reminds me of Vermeer's broken touches of paint. Certain areas are left more unfinished which you can't really appreciate in this photo.
It's hard to find photos of this painting online so hopefully this is useful to some fellow Bouguereau fans. I'm going to try a figural work sometime soon inspired by my experience seeing these paintings.