one's heart, mind, true motives

an Earthling; a Terran

One should be able to derive new understanding while revising what he has learned. Learning from the past.

Central European Time

extraterrestrial area

practical test

experimental device; experimental equipment

on-the-spot investigation

faithfulness, loyalty, devotedness / hardworkingness, painstakingness, diligence / healthiness, fitness

epicenter(AmE), epicentre(BrE) - the point on the Earth's surface directly above the focus of an earthquake. / (figuratively) The focal point of any activity, especially if dangerous or destructive .