The same thing which is the cause of the attainment of the object of man is (sometimes) also the cause of his ruin. The effect of human acts therefore is doubtful.
स एव हेतुर्भुत्वा हि पुरुषस्यार्थसिद्धिषु। विनाशेऽपि स एवास्य संदिग्धं कर्म पौरुषम्॥