read between the lines
“Reading between the lines” is an idiom that is used when someone is trying to determine the real meaning of something…AKA “making an inference”!
One possible origin of this saying comes from the days of military letters and writing, which were often written in a coded form. For those that intercepted them and did not know the code, it looked like total nonsense. Therefore, lots of people started to think that there must be meaning hidden in the other lines (the bits between the lines) in invisible ink. Hence the phrase “to read between the lines” to find the real meaning of something stuck.
Here is an example sentence using the phrase “reading between the lines”:
Sasha was enjoying the mystery book her friend gave her, especially attempting to read between the lines to find clues to determine the culprit.