We quantify the relative proportions of chemical elements in biosystems (e.g., cells, lakes) to gain a systems-level perspective of biology at the lowest level of organization (elemental data are indeed compositional). Such information is necessary to utilize our detailed (though modular) understanding of elements at lower levels of biological organization to make predictions about higher order biology. We call the study of biology from this elemental (as opposed to organismal) perspective, atom-first biology. Atom-first biology is not a new field. First and foremost, it is a mantra to remind ourselves of the imperceptible processes that drive biology, regardless of the level of inquiry. Secondly, it is a call to leverage existing (often longstanding) information about the inorganic chemistry of biological systems. We take this view of biology to develop theoretical, empirical, and analytical approaches for advancing understanding/prediction of any bio/ecological phenomenon.