We've really pushed ourselves in all areas and truly believe that this album is a step up from any of our previous work..."[2] Unlike Aquarius and Visions, for which vocalist Ross Jennings wrote all the lyrics, The Mountain features contributions by every band member.

On a 2016 interview, Jennings said:[3] "I'm still not sure if the rest of the band fully understood what I was trying to achieve lyrically with Aquarius and Visions, which I think left them quite cold and therefore they couldn't relate to those albums so well.

"[4] Drummer Raymond "Ray" Hearne added that "The Mountain set out on a few different lyrical paths before realising its final form.

[4] The first is based on the history of Icarus and covers the subject of "ambition, failure and perseverence [sic], using the metaphor of wings and flying too close to the sun to represent how we take on challenges in life and the desire to prove something to people.

"[4] A shortened version of "Cockroach King" received a promotional video with The Muppets-like band members manufactured by Griffiths and controlled by Rinaldi and Ross.

Conor Fynes of Prog Sphere called it "quite possibly the greatest statement in progressive metal yet released in 2013", and noted that "the influence of bands like Dream Theater and King Crimson are undoubtedly evident, but Haken have finally claimed ownership of a sound unto their own.

[12] He however criticized the lyrics, saying they "tend to feel as cheesy and heavy-handed as they have always been", though still noting songwriting improvements compared to the previous two albums.

"[13] Steven Reid of Sea of Tranquility said the album is "blindingly technical", but "doesn't feel like an exercise in how to get the most notes out of any given instrument".

"[14] However, he praised some songs, such as "Cockroach King", in which he noted vocal influences of Gentle Giant and "Because It's There", described by him as "an example of highly skilled writing and arrangement".