Frank Ocean’s appearance on JAY-Z’s new album 4:44 gives fans a revealing glimpse into the depths of his mind. Ocean is featured on Jay’s track “Caught Their Eyes,” which—like the rest of the album—is produced by No I.D.

On the chorus, he sings about the philosophical theory of solipsism:

Solipsistic admit it, I see you there

So it seems, so you seem

I can’t tell if you’re image or are just the flare

In my dreams, in my dreams

Solipsism is the belief that only one’s own thoughts and experiences are real. Its name comes from the Latin words “solus” (meaning “alone”) and “ipse” (meaning “one’s self”). Solipsism is a strange belief system because although it sounds absurd on the face of it, it’s also notoriously difficult to disprove logically. If the only thing anyone can be totally sure of is their own perceptions, then nobody can ever truly know if their experiences of other people and things are just simulations generated by their own mind.

Solipsism is not just an abstract theory of reality, it’s also a possible psychological experience. Some people with mental illness or serious neurological damage insist that they are the only entity in the world. This is most often caused by long periods of isolation from other humans, and is medically recognized as Depersonalization-Derealization Syndrome. However, the philosophical and medical ideas of solipsism are not necessarily linked; someone can subscribe to solipsistic beliefs without having a mental illness, and vice versa.

Normal people have solipsistic moments in life, too. Colloquially, it’s often used as a synonym for egotism or narcissism when describing someone who shows little regard for others. This may be what Ocean is referencing, but it’s also possible that he often has solipsistic experiences. Although he has never directly used the term in his music before, Ocean has expressed solipsistic ideas throughout his career.

On his 2012 Channel Orange track “Pink Matter,” Ocean ponders the relationship between his brain and his consciousness:

What do you think my brain is made for

Is it just a container for the mind?

This great grey matter

Later on, he questions the objective nature of reality as he perceives it:

What if the sky and the stars are for show

And the aliens are watching live

From the purple matter?

Blonde’s “Seigfreid” features Ocean singing about his discomfort with society and his inability to relate to other people:

I couldn’t gauge your fears

I can’t relate to my peers

I’d rather live outside

I’d rather chip my pride than lose my mind out here

He even asserts that his life is the product of someone else’s vision:

Been living in an idea

An idea from another man’s mind

On “Futura Free,” he encourages listeners to exercise control over their own reality:

You could change this track now

Could’ve changed this bitch a long time ago

Know and know

Clearly solipsistic thinking is part of Ocean’s life, although the extent to which he subscribes to the belief system remains unclear.

Read all the lyrics to JAY-Z’s “Caught Their Eyes” featuring Frank Ocean on Genius now.