therein lies something
From Longman Dictionary of Contemporary Englishtherein lies somethingtherein lies something formalCAUSEused to say that something is caused by or comes from a particular situation The treaty was imposed by force, and therein lay the cause of its ineffectiveness. → thereinExamples from the Corpustherein lies something• The treaty was imposed by force, and therein lay the cause of its ineffectiveness.