The reason I added that quote, by the way, was because although nowadays people typically use "ignorance is bliss" as a blanket justification for willful ignorance, intellectual laziness, or avoiding uncomfortable truths, when English poet Thomas Gray coined the phrase in his 1742 poem (Ode on a Distant Prospect of Eton College), he was expressing a sentiment about the inevitable loss of childhood innocence.
Yet ah! why should they know their fate?
Since sorrow never comes too late,
And happiness too swiftly flies.
Thought would destroy their paradise.
No more; where ignorance is bliss,
’Tis folly to be wise.
And yes, I knew I'd be downvoted for it.
To each his suff'rings: all are men,
Condemn'd alike to groan