יַכְּכָ֣ה יְהוָ֔ה בְּשִׁגָּע֖וֹן וּבְעִוָּר֑וֹן וּבְתִמְה֖וֹן לֵבָֽב׃
The LORD will smite thee with madness, and with blindness, and with astonishment of heart.
Read kabbalistic (mystical) interpretation of Deuteronomy 28:28: and classical mystical sources.