Gustav Fechner
Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.
Modern Stoicism
Modern Stoicism has developed in the context of the 20th-century surge of interest in virtue ethics in general. "The [...] work by philosophers like Philippa Foot, Alasdair MacIntyre, and Martha Nussbaum, among others, have brought back virtue ethics as a viable alternative to the dominant Kantian-deontological and utilitarian-consequentialist approaches." Modern Stoicism draws a lot from the late 20th and early 21st century spike in publications of scholarly works on ancient Stoics. Beyond that, “the Modern Stoicism movement traces its roots to the work of Dr Albert Ellis, who developed Rational Emotive Behavior Therapy, as well as Aaron T. Beck, who is regarded by many as the father to early versions of Cognitive Behavioral Therapy. Viktor Frankl also found stoicism useful while he was imprisoned in a Nazi concentration camp during World War II; he later developed his theory known as logotherapy.