This study examined Leonardo da Vinci's nature-based epistemology as a philosophical framework for understanding how direct engagement with the natural world serves as a source and validator of knowledge, and evaluated its relevance for contemporary epistemology, education, and ecological consciousness. Employing a mixed-methods approach, the research combined systematic qualitative analysis of da Vinci's primary manuscripts with quantitative investigation of 385 educators, scientists, artists, and philosophy students across European and North American institutions. Participants completed validated instruments measuring Nature-Based Knowledge Acquisition (NBKA), Epistemological Validity Perception (EVP), Interdisciplinary Integration (II), Contemporary Application Potential (CAP), and Ecological Consciousness (EC). Univariate analysis revealed above-midpoint endorsement of all constructs with highest means for Ecological Consciousness (M=3.84) and Contemporary Application Potential (M=3.71), though Epistemological Validity Perception showed comparatively lower acceptance (M=3.45), indicating persistent rationalist skepticism. Bivariate correlations demonstrated significant positive relationships among all variables (r = 0.491 to 0.689, p < 0.01), with NBKA most strongly correlated with CAP (r = 0.689). Structural equation modeling revealed excellent model fit (CFI=0.961, RMSEA=0.048) and confirmed that NBKA powerfully predicted EVP (β=0.671, p