Common folks tired with traditional Western spirituality often look to the East--to Buddhism, Vedanta, or forms of Yoga--for more expansive takes on the spiritual and mystical. Or else they (more commonly nowadays) submerse themselves in eclectic mixes (or mishmashes) of various New Age, New Thought, and/or Neopagan hybrids that draw from Eastern spirituality, pop culture, folklore, and fakelore. Mysticism and spirituality focused on nondualism and self-actualization, however, is hidden as it were, in the Western Mystery Tradition and dates back to at least the time of Pythagoras, who lived about the same time as Buddha. A strand of the philosophy and mysticism of the pre-Socratics, including Pythagoras, carried over into Neoplatonism, a type of thinking first attributed to Plotinus, who lived in the third century of the common era (about the time that Christianity started to gain legitimacy and become standardized). With the rise of Christianity, however, the work of Plotinus and those who followed him, such as Iamblichus, was sidelined to be picked up and reframed centuries later during the Italian Renaissance.
I came across this insightful YouTube presentation of Plotinus' discourse on Time and Being. Truths spoken by a largely forgotten Western seer thousands of years before Buddhist or Vedantist thought hit this side of the globe.
