There are no indecipherable writings, any writing system produced by man can be read by man.
Yuri Knorozov on Writing
Attribution
Quotes and notes from Wikiquote: Yuri Knorozov (page history), available under CC BY-SA 4.0.
Quotes and notes from Wikiquote: Yuri Knorozov (page history), available under CC BY-SA 4.0.