The Left Angle Cross of Endeavor is named for Gate 48 and Gate 21. Human Design reads Gate 48, from Hexagram 48, The Well, sitting in the Spleen, as depth, a well of instinctive knowledge that is not yet useful, and a fear of being inadequate to what is asked; and Gate 21, from Hexagram 21, Biting Through, sitting in the Heart or Will centre, as the will to control material life on one's own terms. It sits in the Left Angle family, and Human Design reads that group as outward facing, less a chosen plan than a role other people keep handing back.
Its design half is Gate 53 and Gate 54, both seated in the Root. Gate 53 is read as the pressure to begin, an impulse with often no interest in seeing a thing through; it pairs with Gate 42 in the channel of Maturation. Gate 54 is read as ambition, the drive to rise and transform one's material circumstances; it pairs with Gate 32 in the channel of Transformation.
So a chart carrying this cross senses its own unspent depth while controlling resources on the surface, while beneath it a raw beginning presses against a rising ambition. The same pair also underlies the Cross of Control and the Cross of Depth, and this cross's own reversal is the Left Angle Cross of Endeavor. The numbers are inherited from the I Ching; reading them as one cross belongs to the modern reading, not the classical one.