from Wikipedia:

“Influence of Schopenhauer on Tristan und Isolde

Wagner’s friend Georg Herwegh introduced him in late 1854 to the work of the philosopher Arthur Schopenhauer.[18] The composer was immediately struck by the philosophical ideas to be found in “Die Welt als Wille und Vorstellung” (The World as Will and Representation), and the similarities between the two men’s world-views became clear.[19]

Man, according to Schopenhauer, is driven by continued, unachievable desires, and the gulf between our desires and the possibility of achieving them leads to misery while the world is a representation of an unknowable reality. Our representation of the world (which is false) is Phenomenon, while the unknowable reality is Noumenon: concepts originally posited by Kant. Schopenhauer’s influence on Tristan und Isolde is most evident in the second and third acts. The second act, in which the lovers meet, and the third act, during which Tristan longs for release from the passions that torment him, have often proved puzzling to opera-goers unfamiliar with Schopenhauer’s work.

Wagner uses the metaphor of day and night in the second act to designate the realms inhabited by Tristan and Isolde.[20] The world of Day is one in which the lovers are bound by the dictates of King Marke’s court and in which the lovers must smother their mutual love and pretend as if they do not care for each other: it is a realm of falsehood and unreality. Under the dictates of the realm of Day, Tristan was forced to remove Isolde from Ireland and to marry her to his Uncle Marke—actions against Tristan’s secret desires. The realm of Night, in contrast, is the representation of intrinsic reality, in which the lovers can be together and their desires can be openly expressed and reach fulfilment: it is the realm of oneness, truth and reality and can only be achieved fully upon the deaths of the lovers. The realm of Night, therefore, becomes also the realm of death: the only world in which Tristan and Isolde can be as one forever, and it is this realm that Tristan speaks of at the end of Act Two (“Dem Land das Tristan meint, der Sonne Licht nicht scheint”).[21] In Act Three, Tristan rages against the daylight and frequently cries out for release from his desires (Sehnen). In this way, Wagner implicitly equates the realm of Day with Schopenhauer’s concept of Phenomenon and the realm of Night with Schopenhauer’s concept of Noumenon.[22] While none of this is explicitly stated in the libretto, Tristan’s comments on Day and Night in Acts 2 and 3 make it very clear that this was, in fact, Wagner’s intention.[citation needed]

The world-view of Schopenhauer dictates that the only way for man to achieve inner peace is to renounce his desires: a theme that Wagner explored fully in his last opera, Parsifal. In fact Wagner even considered having the character of Parsifal meet Tristan during his sufferings in Act 3, but later rejected the idea.[23]

From Awake My Soul,

How fickle my heart and how woozy my eyes
I struggle to find any truth in your lies
And now my heart stumbles on things I don’t know
My weakness I feel I must finally show

Lend me your hand and we’ll conquer them all
But lend me your heart and I’ll just let you fall
Lend me your eyes I can change what you see
But your soul you must keep totally free

Awake my soul, awake my soul

In these bodies we will live, in these bodies we will die
Where you invest your love, you invest your life
In these bodies we will live, in these bodies we will die
And where you invest your love, you invest your life

Awake my soul, awake my soul
Awake my soul
For you were made to meet your maker

(Read more: Mumford & Sons – Awake My Soul Lyrics | MetroLyrics )

It is difficult not to think that rejecting one’s passionate attachment to things of the world is gnostic rejection of material things. Mumford keeps his body engaged, but even he has a thing for death in “After the Storm”:

And I will die alone and be left there
Well, I guess I’ll just go home, oh God knows where
Because death is just so full and man so small

(Read more: Mumford & Sons – After The Storm Lyrics | MetroLyrics )

Hebrews talks about longing for another country, not here. But we become fit for it here through repentance of mind, soul, and body, so it is wrong to seek escape.