In An Experiment with an Air Pump, Armstrong's quotation of "reason not the need" from King Lear to Isobel is highly significant. In King Lear, the phrase is uttered by King Lear himself when he argues that humans are not merely animals driven by basic needs; they have desires beyond survival that define their humanity. In Armstrong’s context, this line underscores his view that scientific progress and knowledge acquisition transcend moral considerations or basic human empathy.

When Armstrong says this to Isobel, it reflects his rationalization of the ethically questionable experiments he performs, particularly on vulnerable subjects like Isobel. He dismisses her personal feelings and dignity, much like Lear dismisses the material needs of others, to justify his pursuit of knowledge. By invoking this line, Armstrong implies that the pursuit of science and intellectual advancement outweighs individual suffering, echoing the play’s theme of humans being reduced to mere function or utility.

This moment also foreshadows Isobel’s eventual fate, suggesting that Armstrong sees her not as a human being with intrinsic value but as a tool for his experiments, further symbolizing her dehumanization and eventual "sacrifice" for science, much like the bird in the opening experiment. The choice of this specific quote adds layers of meaning by connecting Armstrong’s character to the hubristic, tyrannical tendencies of Lear, who also loses sight of compassion in his quest for power and control.