sections [that] turn into this mass orchestrated swarm and ridiculous time signatures" which include musical references to 1970s soft rock bands such as Wings, Eagles and Bread - summed by Hawkins by saying the band "wanted to make sure that everything 'built' on this record, that each instrument started somewhere and went somewhere else in the course of a song". The drummer attributed this to the acoustic tour leading the band to "shed some of the fear of incorporating mellower stuff with the heavy stuff", and Grohl added that "we wanted the stops to be pin-drop silent before exploding. If we had a beautiful melody, we'd throw a fucking string quartet in there. So we did everything we could to really magnify all those elements and that was fun. Usually you have a few parameters you're afraid to pass but, this time, there was no fear of going too far." Mix engineer Rich Costey added that his work to "preserve what [the band] had done to a fairly large degree" with "balancing and rides to get the dynamics to happen" was difficult given the sonic variety of Echoes, which went from "[the Foo Fighters'] endless walls of guitar overdubs, almost like a swarm of bees" to string quartets: "The challenge of this type of mix is to retain the power of the track, yet define a space for everything." As the acoustic tour made Grohl realize "we were making music worth listening to, rather than music made for pummelling the person next to you" he decided to give more importance to the lyrics and "have a connection with the crowd in front of us", considering that among the many compositions the band made on pre-production "the ones that stand out are the ones that say something". So for the first time the lyrics started being written before recording begun, with Grohl stating that he "sat in the back of the studio and just wrote every day for about 14 hours a day." Most of the lyrics of the album deal with themes of birth, death and life, which Grohl attributed to the birth of his daughter Violet, considering that having a child "changes your entire outlook on the world", and that he was suddenly more emotional - "So when you're writing music with that in mind or that in your heart, everything just blooms into this fucking incredibly colourful, colourful