There's hints, it's not just the scripture but also the structure tells hints. Even the environment tells you.

1st Boss looks like a deer it's gonna be something with a deer. (Both hints well)

2nd Boss though the look doesn't give me the hint what kind then what about the pillars that have the shapes that look like a certain item. (Structure gives hint well)

3rd Boss has a shape of a skull hint, look at the start of the entire game and see the boss is a big giant blob, sunken crypt there's dead old blobs to mine and what do I get out of them.(Environment give you a hint well)

There's hints in the game your not using your head.
Not sure what about the fourth and last boss though environments, structure, and scripture tell you the hints to summon like a boss.