to figuratively remove those constraints which narrow one’s field of vision, leading one to consider an issue in its entirety without assuming that current or historical limitations hold sway; the phrase originates from the practice of blocking a horse’s peripheral vision to prevent distraction from the path ahead and to keep the typically flighty animal from startling; can be derogatory in implication if this instruction is directed at a single individual, who is thereby insinuated to be insufficiently creative, flexible, or broad-minded