The Sautrantika school
A school that trusted the Buddha's discourses over later systems—and argued we never see the world directly.
Sautrāntika means roughly "those who follow the sūtras (discourses)." This early school, taking shape in the early centuries CE, defined itself by a stance on authority: it accepted the recorded discourses attributed to the Buddha as binding, but treated the later, highly systematic Abhidharma literature—elaborate catalogues of mind and matter compiled by other schools—as human commentary, not the Buddha's own word. So it refused to grant those systematized "factors of existence" (dharmas) the solid, substantial reality that rival schools gave them.
Its most striking contribution was a theory of perception. The Sautrāntikas argued that we do not perceive external objects directly. By the time a cause out in the world produces an effect in your awareness, the original object has already passed—each moment is fleeting. So what you actually experience is a mental representation or "image" that the object left behind, like a coin pressed into wax. We infer the outer world from these inner impressions rather than meeting it face to face. This is sometimes called representationalism, and it strikingly parallels debates in later European philosophy.
This combination—skepticism toward over-built systems, plus a subtle, economical account of how knowledge works—made Sautrāntika ideas influential well beyond the school itself, feeding into the great Buddhist tradition of logic and epistemology that followed.