Flocking is an emergent phenomenon from whose study the field of active matter arose. The traditional approach to flocking is associated with the Vicsek model, which assumes that particles have a constant velocity magnitude. The consequence of this approach is that the microscopic description already incorporates many of the characteristics of the continuum behavior, thereby undermining the notion of emergence and obscuring the origin of activity. In this seminar, I will discuss a completely different approach to active matter which involves a microscopically reversible model with reactive collisions between bird and air particles, both modeled as hard spheres, and I show that by turning on the "chemostat", such a model can display a flocking transition.