The letter Y represents an intermediate between the celestial and the spiritual in man, especially in the heavens. Historically, it is closely connected to I and J in English, particularly when it's the initial letter in a word. When it's made with curves, a letter has something of the celestial in it. (Spiritual Experiences 5620, Doctrine Regarding Sacred Scripture 90)

91. Heresies May Be Seized On from the Word’s Literal Sense, But It Is Harmful to Affirm Them

We showed above that the Word cannot be understood apart from doctrine, and that doctrine serves as a lamp in whose light genuine truths may be seen. And the reason is that the Word was written solely in terms of correspondences. As a result, the Word contains many appearances of truth that are not naked truths, and much was accommodated to the comprehension of natural people, even of sensual people, yet at the same time it was written in such a way that simple people can understand it in simplicity, and wise people wisely.

Now because that is the nature of the Word, the appearances of truth, which are truths clothed, may be seized on as naked truths. And when these are affirmed, they become falsities.

People who do this, however, are people who believe themselves wiser than others, even though they are not wise. For it is the part of wisdom to see whether something is true before affirming it, and not to affirm whatever one pleases. People who do the latter are people who possess a talent for defending their affirmations and are caught up in a conceit in their own intelligence. But those who do the former are people who love truths, who are affected by them because they are true, and who apply them to useful life endeavors. For they are enlightened by the Lord and see truths in the light of those truths, in contrast to the first people who create their own enlightenment and see falsities also in the light of those falsities.