Mirrors start to whisper, shadows start to sing?
Look, I don't care how artistic this may come across to some people, but this is fucking retarded.
Retarded, would suggest a complete lack of logic.
Those lyrics were composed, I understand, in regards to what are known as, K-trips.
K being, Ketamine, a dissociative drug, that has the implication of effectively inciting psychosis.
It does this via blockade of an amino acid receptor subtype called, N-methyl-D-Apartate, (NMDA) which has a downstream effect of increasing the amino acid transmitter, Glutamate - its release.
Glutamate is an excitatory neurotransmitter, thus it incites release of excitatory co-transmitters, namely, dopamine and noradrenaline.
Excesses of dopamine in the nigrostriatal dopamine pathway, it what gives rise to the psychotic effects of ketamine, much the same way that schizophrenia, the illness, induces psychosis.
Ketamine is used clinically to study psychosis, as its effects are virtually indistinguishable from the illness itself.
Psychosis being, delusions, halluciations, visual and auditory - a separation from what is transpiring on a realistic level, similar to, say, delving deeply into an imaginatory process.
This is represented figuratively via "mirrors", objects that have been used to convey or enhance the perception of supernatural entities - something that can take us away on a tidal wave of imagination - and these mirrors are exaggerating that representation, via whispering.
And shadows, used often times to convey mystery, representation of things unknown, alternate states of self, alternate roles or possibilities - those things that may exist on the spectrum of imagination - these shadows, singing - coming to life; those imaginations, the break away from the mundane, to make the supposedly unrealistic, come to realistic fruition; which could hypothetically represent a break away from some cultural incarnation of a locked-in-syndrome, deviation from cultural norms, introduction of new thought paradigms and thus, ways of life. Reformation of primitive and inhibitory belief patterns.
So, by definition - "mirrors start to whisper, shadows start to sing" - it could be interpreted in several ways, a figuration subjectively dependent on the personalized aspiration.
But, lack of sound logical application, rational, and clear meaningful thought processes being the inference of word - of all things these two lines could represent - "retarded", is pretty much the antithesis of it.