The description of single constructs and single examples originally had felt unrelated to the reality of the nurse's world. They oversimplified its complexity. The nature of nursing was complex. It seemed to me that we needed, as a profession, constructs that simplified and allowed clear communications. We, also, needed constructs that conveyed the reality and complexity of the {110} worlds in which nurses nursed. Perhaps a description of what "all-at-once" expressed for me would convey to others the lived-unobservable-worlds of nurses. Nurses relate to other man in situations of "all-at-once." The "all-at-once" is equated by me to Buber's "I-Thou" and "I-It" occurring simultaneously and not only in sequence as he expressed it. These two ways that man can relate to and come to know his world and himself demand sequential expression for clear communication. However, the responsible authentic nurse in the nursing arena lives them "all-at-once." Aware of the multifarious multiplicities of her responses to another and at once to the surrounding field of action, the nurse selects and overtly expresses her responses that actualize the purpose, values, and potential of the artful science of professional nursing. Awareness of the multifarious multiplicities affecting the other and the self in the nursing arena is a component of "I-Thou" relating. Selectively overtly expressing concordantly with the purpose, values, and potential of nursing necessitates a looking at, which is a component of "I-It" relating, while acting and being. Therefore both "I-Thou and I-It" modes of being are "all-at-once." This necessity for a nurse's duality in her mode of being came to my awareness through comparing Gilbert' and Muller's works, studying Buber's conceptions of man, and considering them in relation to my current and past lived-experiences in the nursing-arena. In my nursing world of "I-Thou" relating reflection is called forth prior to my overt response to allow response selection concordant with my nursing purpose. The very character of multifarious multiplicities of the nursing world undoubtedly has called for nurses to develop their human capacity for duality in their mode of being.