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This paper discusses the possibility that the intensities of the [N II] emission lines at 6548 and 6584 \AA\ are boosted, in a variety of astrophysical nebulae, by the $(2s^{2}2p^{2}) \ ^{1}D_{2}$ --- $(2s^{2}2p3s) \ ^{3}P^{o}_{1}$ transition at 748 \AA. According to theoretical calculations by Fawcett and experimental measurement of the branching ratio, this intersystem ($\Delta S \neq$ 0) transition is as fast as a typical electric dipole allowed transition. The $(2s^{2}2p3s) \ ^{3}P^{o}_{1}$ level is directly populated by a resonance transition from the $(2s^{2}2p^{2}) \ ^{3}P$ ground state, and one out of three electrons that enter the $(2s^{2}2p3s) \ ^{3}P^{o}_{1}$ level will spontaneously decay through the 748 \AA \ transition. Since the 748 \AA\ transition deposits electrons in the $(2s^{2}2p^{2}) \ ^{1}D_{2}$ level from which the [N II] $\lambda \lambda$6548,6584 emissions originate, this remarkably strong intersystem transition will increase the intensities of the famous [N II] temperature diagnostic emission lines if significant excitation of the $(2s^{2}2p3s) \ ^{3}P^{o}_{1}$ level occurs. We discuss the circumstances in which the $(3s) \ ^{3}P^{o}_{1}$ upper level could be significantly populated by photoexcitation, collisional excitation, or recombination. We point out that detection of recombination lines that feed the $(3s) \ ^{3}P^{o}_{1}$ level provides direct evidence that this process is important in nova shells. We also discuss the possible importance of this process in the production of anomalously large [N II]/H$\alpha$ ratios in cooling flow emission line filaments and starburst galaxy superwinds.
