The Pennsylvania System, developed in the early 19th century, was a method of prison reform that emphasized rehabilitation over punishment. It aimed to encourage reflection and moral improvement by isolating inmates in individual cells, allowing them to engage in solitary contemplation. This approach was designed to reduce recidivism and promote better behavior among prisoners. The system was first implemented at the Eastern State Penitentiary in Philadelphia, which became a model for other institutions. While it had noble intentions, critics argued that prolonged isolation could lead to mental health issues, leading to a decline in its popularity by the late 19th century.