Phenomenological language means speaking of the appearance of a thing although this is not its real nature. For example, consider this sentence:He looked down from his penthouse window, watching all the tiny people rushing off to their jobs.The people described in this sentence are not actually any smaller than normal. The author does not intend to indicate that they are, nor does the reader understand it that way. They both realize the people look small because they are far away.A similar way of using language occurs in this situation, in which a mother speaks to a young child:“You stay here with Daddy. Do you see that little tree over there? Mommy is going to be near there, and will be back for supper time.”In this case too, the tree looks smaller than it really is because of distance. The child, however, is too young to understand perspective and does not realize that his mother is talking about a tree that is actually big. The mother is not lying to the child, but telling the truth using terms the child will understand. The mother intends to convey a message to reassure the child that she will return. She is not talking about the size of trees.According to Providentissimus Deus, Scripture sometimes uses this kind of language:“Ordinary speech primarily and properly describes what comes under the senses; and somewhat in the same way the sacred writers-as the Angelic Doctor also reminds us - `went by what sensibly appeared," or put down what God, speaking to men, signified, in the way men could understand and were accustomed to.”
Note that this idea is not some novelty introduced by Pope Leo XIII, but a teaching going back at least as far as St. Thomas Aquinas. This interpretation is not an attack on the inerrancy of Scripture. It is not a lie or error to describe things according to how they appear to our senses or put into terms that one’s readers can understand, even when the appearance is not the same as the inner nature. To apply this to a specific passage of Scripture, let’s look at this one from the first chapter of Genesis: [6] And God said: Let there be a firmament made amidst the waters: and let it divide the waters from the waters. [7] And God made a firmament, and divided the waters that were under the firmament, from those that were above the firmament, and it was so. The Church does not expect us to take this literally, since it is contrary to reason. Therefore, we may interpret it as speaking of how things appeared to people at the time it was written. To them, it appeared as if there were a hard, clear dome above the earth which had water on the other side, giving the sky the same colour as water in lakes and rivers. This water could come to the earth as rain. The hard dome is what held the lights in the sky in their places: the sun, the moon, and the stars.
As stated in PD, “the sacred authors and the Holy Ghost who spoke through them…did not seek to penetrate the secrets of nature.” The point of this passage and its larger context is to say that everything that we see was created by God, by deliberate act, and God made His creation good.
This message was in contrast to surrounding pagan mythology which explained creation as a random, violent event. They said things like the gods had battled and blood from their wounds made the world. It was all a big accident.
Just as the mother in the example above was not trying to teach her child about the size of the tree but to reassure him, Scripture is not trying to teach that the sky is a hard dome but to reassure us that creation was not random. God wanted to make everything that we see around us. God made it and it is good.
This message is as important now as it was when it was written. We too live surrounded by people who believe a creation myth based on randomness, which is what atheistic evolution is. We need to focus on the point of the story, rather than try to turn Genesis into a science book.
This way of understanding Genesis is explicitly allowed by Pius X:Question 5. Must each and everything, namely, the words and phrases, that occur in the aforesaid chapters always and of necessity be interpreted in the literal sense, so that it is never permitted to deviate from it, even when expressions are manifestly used not literally (but) metaphorically or anthropomorphically, and when reason forbids us to hold, or necessity impels us to depart from, the literal sense?
Response: No.
https://thesocraticcatholic.com/2017/02/08/pope-st-pius-x-responses-of-the-biblical-commission/