Keel (bird anatomy) keel; and ratites (from "ratis", "raft" — referring to the flatness of the sternum), having a subtle keel structure or lacking one entirely. However, this classification has fallen into disuse as evolutionary studies have shown that many flightless birds have evolved from flighted birds. The current definition of Carinatae now includes all extant birds. Keel (bird anatomy) A keel or carina (plural carinae) in bird anatomy is an extension of the sternum (breastbone) which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the ribs. The keel provides an anchor to which a
Answering the Question: What is Enlightenment? II of Prussia for creating these preconditions. Kant focused on religious issues, saying that "our rulers" had less interest in telling citizens what to think in regard to artistic and scientific issues. Kant answers the question in the first sentence of the essay: "Enlightenment is man's emergence from his self-incurred immaturity (Unmündigkeit)." He argues that the immaturity is self-inflicted not from a lack of understanding, but from the lack of courage to use one's reason, intellect, and wisdom without the guidance of another. He exclaims that the motto of enlightenment is "Sapere aude"! – Dare to be wise! In the