Liar is an early rock epic written by Mercury. As the legend says it is an updated version of an Ibex-era song called "Lover". It's harmony is very simple, its form is clever, and the rhythm department has its share of tricks as well. The simple harmony is a result of Freddie composing it on guitar, including probably most of the basic guitar riffs as well.
The re-intro divides the song to two parts with hardly any musical cross-references. The first half of the song has relatively ordinary ballad form of two cycles with short Verses.
The song starts with an instrumental multi-intro. Its first subsection is purely rhythmic, it builds on the 3+3+3+3+4 pattern of eigths repetead six times. The sevent cycle departures into a drum roll.
The second subsection consists of four two measure cycles of guitar riffs with a AA'AA" form. The pitch set (see next subsection as well) suggest an A mixolydian key. The riff uses bluesy "blue" third (m3>M3).
The third subsection consists of four harmonic phrases (ABB'C 4+2+2+4) the last of which is featuring arpeggiated guitar with stepwise moving inner line over pumping pedal bass. Getting its exact length is difficoult by just counting the 1/4 beats, rather you do this math: 2+3+3+3+3+3+3+3+3+3 = 32 x 1/8 = four measures.
The fourth subsection dominated by another "classic rock" style riff developed in four cycles with minimal changes. The tonal centre is shifted to E.
which is a variant of the 2+3+3+3+3+2 pattern.
The next four phrases add bass guitar doubling the riff (E*) and lead guitar over it. Organ (no synth!) chord is fading in.
The last fourth phrase we have a diatonic parallel harmony for three guitars and more of the 3+3+... grouping of notes with 4/4 backing beat on drums and pulsing pedal bass on E. The rising pattern: one step down, two steps up (see also "...Wild Wind").
The figure arrives on D major triad, the ronic of the homekey of the song. The length of this phrase is 3 x 10 = 30 x 1/8 resulting in a 3/4 measure closing the phrase.
The fifth subsection starts with the closing D major guitar harmony with organ doubling it. The arpeggiated acoustic guitar figure (early Queen favourite) backing of the forthcoming Verse is fading in.
With some changes it reprises the midle subsections of the intro til the rising arpeggio section with extra guitar counterpart added roughly paralelling the ascending inner line of the arppeggio. It is followed by Chorus 2.
The verse is only four measures. Phrasing: 2+2 AA' (subphrasing: XYXZ, see also "Killer Queen").
The second Verse alters the pentatnonic lead melody of the second phrase. The acoustic guitar arpeggios are changed to electric guitar chords with many off beat accents. The last measure adds a maj7 dissonance.
The chorus starts with an acappella measure with the signature title phrase sung in a powerfull three part harmony, which is the heart of the Chorus and the whole song (see also "Flash"). The phrasing is 4+4 AA'. Harmony-wise it looks like a bridge with no tonic except the ending overlapped by the Verse.
The second chorus is added an extra phrase for the resolution provoked by the lack of a following verse.
After the re-intro there is no Verse, we run straight into an alternate chorus with three distinct subsection. We have lots of title phrases with various harmonies over the same rhythm. The first subsection consists of six phrases (2+2+2+2+2+2, AABBCC), where the title phrases are located in the uneven numbered measures, antiphonal vocals in the even numbered ones. The last two phrase has slower backing beat and descending bassline instead of chords. Note the chormatic tune in measures 10 and 12.
The next subsection lacks any harmonized title phrases. Its phrasing is 2+2+4, A B A-ext.
The last subsection is only one phrase. I transcribed it in five 3/4 measures.
After a drum roll the first subsection is repetaed with halved tempo lead vocal, and the last for measures occupied by the first subsection of the solo.
The first subsection (four measures m1-4) is an instrumental version of m9-12 of the Chorus. There is a second lead guitar beside the main one.
The second subsection (m5-14) starts with double tracked unisono guitars departuring first in m.11.
In the next sub section (m15-22) we have three guitars moving sometimes parallel sometimes contrapuntal. Note the use of both melodic 3rd and flat-3rd degrees next to eachother in m15-16.
A pre-bridge connector closes the solo section with bass guitar doubling guitar.
The last two measures expose the percussion backing of the Bridge.
The bridge is dominated by two measure phrases (AA'ABB'B...) closing with antiphonal "all day long" harmonies. These harmonies are sung with double frequency (ie. sung in each measure) from m.13. Along these harmonies Brian plays the "Hendrix" chord (E7b9 notated as E*) with varying rhythm and timing.
The first subsection is dominated by a two measure riff repeated four times.
The riff involves a relatively hard to hear ascending inner line. In the fourth cycle a bas stops doubling the guitar and starts a stepwise ascending motion. For m1-6 of the next subsection it changes to an oscillating figure while guitar play descending chord progression. In m7-11 the bass executes a scalar walk down while guitar sustains treble pedal point. The key is e-minor.
We have a pivot modulation to D Major. The inverted pivot chord is perhaps the most "jazzy" point of the song dominated by simple harmony.
We have a third "Liar" sections with some antiphonal title phrases again. Both phrase pairs 1-2 and 3-4 show the same ABAC-type melody development.
The chorus 3 is gradually transforms into an outro wich starts with the slow scalar descent familiar from Chorus 2.
The descent arrives surprisingly to F.
In the instrumental last phrase has no backing beats anymore. Brian May plays guitar figures with lots of pull on - hammer on and sliding up and down without a single string-picking. It was a legendary Hendrix lick.
Beyond the lead guitar sus4 dissonances are played.