Thomas Edison is best interpreted as ESTJ when his personality is translated into the four-letter MBTI framework through the typological principles described by Jung in Chapter X of Psychological Types. The important point is that Jung did not define psychological type by occupations, intelligence, productivity, or visible behavior alone. The decisive question is the direction of the dominant psychological function and the criterion by which judgment is formed. In Edison's case, his characteristic approach to invention strongly resembles Jung's extraverted thinking type, supported by an empirically oriented sensing attitude. Jung describes the extraverted thinking type as someone whose activities are governed by intellectual conclusions that are ultimately oriented toward objective data, external facts, or generally accepted ideas. Such a person attempts to elevate an objective formula into something that can organize reality itself. This is highly relevant to Edison because his approach to invention was fundamentally practical and externally oriented. He was not primarily interested in maintaining an internally elegant theory. His ideas had to work in the physical world. This distinction is important because Edison is sometimes typed as an INTP or another introverted thinking type simply because he was highly analytical and inventive. But intelligence and analytical ability do not establish Ti. Jung specifically distinguishes extraverted and introverted thinking according to orientation. Extraverted thinking is guided by objective data and tends to return its conclusions to external facts, whereas introverted thinking begins from the subject and develops an internally oriented conceptual structure. Edison's famous experimental approach fits the former much better. He repeatedly tested ideas against physical reality, modified designs according to results, and treated experimentation as a means of converting hypotheses into functioning inventions. This is not the profile of someone who merely wants to construct a logically satisfying internal model. His thinking was continually pulled back toward the external object: the machine, the material, the electrical system, the manufacturing process, and ultimately whether the invention actually worked. That also explains why ESTJ is more appropriate than ENTJ in the four-letter system. The E and T components are relatively straightforward: Edison appears strongly extraverted in his orientation toward projects, organizations, laboratories, workers, business, and practical implementation, while his dominant mode of judgment was clearly thinking. The more difficult question is S versus N. Here, his attention to concrete experimentation and tangible mechanisms makes S the stronger choice. Jung's description of extraverted sensation is useful for understanding what S does and does not mean. An extraverted sensation orientation is intensely connected to objective reality and concrete experience. Its consciousness is closely tied to what can actually be encountered in the external world. Edison does not resemble the pure sensation type because thinking was clearly much more differentiated in his personality. However, the practical, empirical character of his perception provides a useful basis for understanding an ESTJ rather than an ENTJ interpretation. His inventions were not simply expressions of abstract visions detached from immediate reality. They emerged through contact with materials, machines, measurements, failures, and observable results. Even when Edison pursued enormous projects, his attention repeatedly returned to concrete implementation. The question was not merely whether an idea was conceptually possible, but how it could be constructed, tested, improved, standardized, and introduced into practical use. This is also where Edison's entrepreneurial behavior becomes relevant. Jung states that practical thinking in the businessperson, technician, and scientific investigator is an obvious example of externally directed thinking because its orientation repeatedly returns to objective data and external facts. Edison represents an unusually strong combination of these domains. He was simultaneously an inventor, experimentalist, organizer, and businessman, meaning his thinking naturally operated across the entire chain from objective problem to practical solution. An ESTJ interpretation does not imply that Edison lacked imagination or intuition. Jung's model does not require other functions to be absent. He explicitly explains that a dominant conscious function is accompanied by an auxiliary function, and that practical thinking can be combined with sensation while other functions remain comparatively less differentiated. Therefore, Edison's creativity should not automatically be interpreted as evidence for dominant intuition. The strongest case for ESTJ is therefore not that Edison was "organized" or "productive." Those are superficial stereotypes. The deeper case is that his psychological orientation repeatedly moved from objective problems toward externally verifiable solutions. He valued experimentation, measurable results, practical implementation, and the transformation of ideas into functioning systems. His thinking was not satisfied with remaining inside an abstract conceptual world. In Jungian terms, Edison therefore resembles the extraverted thinking type much more than the introverted thinking type. His thinking was oriented toward the object, while his practical sensing gave that thinking a concrete and empirical character. When translated into the modern four-letter MBTI framework, this combination most naturally corresponds to ESTJ. The label should not be taken as a claim that every aspect of Edison's personality fits a modern MBTI stereotype. Rather, ESTJ is the closest four-letter approximation of the Jungian structure suggested by Chapter X: an externally oriented thinking type whose judgment is continually tested and expressed through concrete reality.