In 1951, when Maria Montessori described the pattern of human development as the Constructive Rhythm of Life, marking each of four chapters or planes of development with an inverted triangle, she colored the first and third planes red to represent their intensity (Grazzini, 1996). These two red triangles are referred to as creative periods and represent early childhood and adolescence, times of life that involve intense development and rapid brain changes (Goddings & Giedd, 2014). Blue triangles mark the second and fourth planes of development, representing the more stable growth of the elementary school years and the relative maturity of early adulthood. Today, neuroscientists have confirmed what Montessori astutely observed: that the red creative periods involve structural and functional brain changes that create temporary upheaval in exchange for a more efficient brain to emerge, finely tuned for the next stage of life (Goddings & Giedd, 2014; Grazzini, 1996). Beyond adolescence, the third plane of development, lies the calmer waters of maturity--the fourth plane. While development is known to continue into adulthood, it has largely been thought that adults are no longer thrust into the destabilization of rapid pruning and tuning that marked the first and third planes of development. But what if there is an event that could precipitate a fifth plane of development, and a third and final creative period? An acute phase of adult development spurred by the need for an entirely new set of skills, necessitated by an entirely new set of priorities? This article discusses the fifth plane of development.