The main point here is not that consciousness unilaterally creates all forms in the [U]niverse, as has been supposed by Dharmapala and [Xuanzang], but rather that an object-of-consciousness is "internal", and the "external" stimuli are only inferrable.
[1]Dan Lusthaus (undated: unpaginated) holds that: Vasubandhu's most original and philosophically interesting treatise is his Twenty Verses (Vimśatikā).
Consciousness is driven by karmic intentionalities (the habitual tendencies produced by past actions), and how we perceive is shaped by that conditioning.
The goal of Yogācāra is to break out of this cognitive narcissism and finally wake up to things as they are, devoid of erroneous conceptual projections.
[2] Tola and Dragonetti (2004, p. 134), in contrast, assert that:Vasubandhu states in first place...: All is only mind, consciousness; there exist only representations, mental creations, to which no external object corresponds.