I am familiar with the concept, and understand the modes as a different tonal center of a key, but that's as far as my knowledge on the subject goes. I'd not know a mode if it came up and asked me for a whirl on the dance floor. I can usually figure out the key of a piece given a few moments and a familiar instrument to play, but it's not automatic for me. Figuring out the modes are a ways off for me.
Agreed on the emotions stirred being cultural, if not downright human nature. Some sounds are hardwired in to generate certain behaviors. We don't learn them. They're innate reactions. One example of this is a wild turkey. The babies of a wild turkey are innately wired to respond to the mother's call. If you had a recording of it, they'd come running to you. They don't know the difference. If you had hatched a group of poults away from the calls of the mother in an incubator, they'd still come running to the sound of a mother turkey's call. Their brains are wired to respond to that sound by moving nearer to it.
If humans of today experience the same emotions triggered by modal scales as in the days of ancient Greece, does that mean we're simply wired that way? Or is it because we've been exposed to them in connection with stories highlighting those emotions in tandem? It remains a mystery.
I do like the idea that to develop a particular emotion in a song, all that's required is to use this mode, or start your chord progression with this scale degree. You want to add some tension here, these chord progressions can help you create suspense, dread, excitement, etc. To lower the energy, stick with the lower bass notes. It's all becoming fairly fascinating. Some of it I want to say is common sense, not in an intellectual sense, but in an emotional sense - when you're playing it you can feel it - that tension building, the release back to home base, etc. It just follows that you'd take advantage of those properties in designing the journey you're building for your listener.
I have to say that I'm glad to be reading the book. It gives me another way of looking at songwriting that goes straight to the point, and it distills the details of which chord progressions work well for this situation, for that emotion, which keys for this and that, etc. It's not easy to find that information all in one place online.
Late to the convo, but I wanted to step in and offer a different perspective on some of your comments to nudge you in a more helpful direction.
I get what you mean about understanding the modes as different tonal centres of a key. But I don't think this is a helpful way of understanding the concept or relating to the function of modes. The two most common modes are the major and minor scales. They don't have different tonal centres. D major and D minor share D as their tonal centre. D lydian though *looks* (on a piano keyboard) like a C major scale, except you start and finish on D. But if you're playing in D lydian, D is your tonal centre (not C). What's changed is the *flavour* of your scale. The notes you'd choose to form chords to accompany your melody. This is true for all the modes.
If you're interested in going deeper, I suggest subscribing to Rick Beato's channel on youtube - he's got loads of great stuff on modes. I think he's going to be an interesting character for you, because he's important in answering your second point about in-utero exposure to sound. Before and after his son was born, Rick played the music of Ayden Esen to him (I think I spelled it right). You need to hear this music to appreciate the education he was giving his (unborn) son. It's incredible stuff. Anyway, the musical 'knowledge' and reaction of his child is striking. This video tells the story
The ideas about using different scales, chords, modulations and so forth to create certain atmospheres and human reactions though is well documented. Musical composition courses are full of this stuff. I'm not sure about using lower bass notes to lower the energy though - low notes contain more energy (which is why they need plenty of space to avoid sounding muddy), but I guess it's all about how you use them. Lower notes usually darken the colour though, maybe that's what you're getting at.
Going back to Boydie's mantra that great songs are re-writes of good songs (which are re-writes of songs), I largely agree.
BUT, with one important caveat: experience. I've begun to appreciate the unique energy of first thoughts. When you pick up your instrument or piece of paper, and begin to create something, it often has a strong energy that's hard to hold onto. I know I've had this experience lots of times, where I've tried to hold onto it, but by the time the song's finished, it's gone. Usually, the song suffers as a result. While I think my best song is one of the ones I worked longest and hardest at, I also have a 'top 5' song which fell out of my brain and fingers in 20 minutes, fully formed. I rewrote one or two lines later on. But the energy of the song definitely stands out.
So while you could deliberately choose to start your song in the mixolydian mode for a particular emotional resonance, there's also a good argument to say you should just sit down with that emotion, and see what falls out of your body. Chances are, it will be worth noticing.