In the context of education, "open(ness)" has become the watermark for a fast growing number of learning materials and associated platforms and practices from a variety of institutions and individuals. Open Educational Resources (OER), Massive Open Online Courses (MOOC), and more recently, initiatives such as Coursera are just some of the forms this movement has embraced under the "open" banner. Yet, ongoing calls to discuss and elucidate the "meaning" and particularities of openness in education point to a lack of clarity around the concept. "Open" in education is currently mostly debated in the context of the technological developments that allowed it to emerge in its current forms. More in-depth explorations of the philosophical underpinnings are moved to the backstage. Therefore, this paper proposes a historical approach to bring clarity to the concept and unmask the tensions that have played out in the past. It will then show how this knowledge can inform current debates around different open initiatives.