I’m a real admirer of Cardinal Nicholas of Cusa. I personally hope that one day he will be recognised as a saint, for his contributions. He was so far ahead of his time.
In the 1400s, he proposed the idea of alien life on other other planets, arguing living beings on other planets would reflect the “elemental composition of those planets”.
Cardinal Nicholas of Cusa wrote:
"…Therefore, just as the earth is not the center of the world, so the sphere of fixed stars is not its circumference – although when we compare the earth with the sky, the former seems to be nearer to the center, and the latter nearer to the circumference. Therefore, the earth is not the center either of the eighth sphere or of any other sphere…Life, as it exists on Earth, in the form of men, animals and plants, is to be found, let us suppose, in a higher form in the solar and stellar regions. Rather than think that so many stars and parts of the heavens are uninhabited and that this earth of ours alone is peopled — and that with beings, perhaps, of an inferior type — we will suppose that in every region there are inhabitants, differing in nature by rank and all owing their origin to God, who is the centre and circumference of all stellar regions. Now, even if inhabitants of another kind should exist in the other stars, it seems inconceivable that, in the line of nature, anything more noble and perfect could be found than the intellectual nature that exists here on this earth and its region. The fact is that man has no longing for any other nature but desires only to be perfect in his own.
Were we to suppose that, for the realization of the plan of the universe, the whole region of the other inhabited stars stands in some relation of comparison, unknown to us, through the intermediary of the universal region a certain relationship springs up from both sides between the inhabitants of this earth or region and the inhabitants of other stars — in the same way as through the intermediary of the hand there exists a relation of comparison between the particular joints of the fingers and the foot, so that all be suitably adapted to the whole animal; not even then with this supposition could we find a relation of comparison between those inhabitants of the other stars, of whatever nature they be, and the natives of this world.
For since that whole region is unknown to us, its inhabitants remain wholly unknown. To go no further than this earth: animals of a given species unite to form a common home of the species and share the common characteristics of their habitat, knowing nothing of or caring nothing for strangers. Their idea of strangers, even if it reaches some kind of vocal expression, is wholly exterior and conjectural and, such as it is, conceivable only after lengthy experience. Of the inhabitants then of worlds other than our own we can know still less, having no standards by which to appraise them. It may be conjectured that in the area of the sun there exist solar beings, bright and enlightened intellectual denizens, and by nature more spiritual than such as may inhabit the moon — who are possibly lunar — whilst those on earth are more gross and material. It may be supposed that those solar intelligences are highly actualized and little in potency, while the earth denizens are much in potency and little in act, and the moon-dwellers betwixt and between.
We make these conjectures from a consideration of the fiery nature of the sun, the water and air elements in the moon and the weighty bulk of the earth. And we may make parallel surmise of other stellar areas that none of them lack inhabitants, as being each, like the world we live in, a particular area of one universe which contains as many such areas as there are uncountable stars. In these local areas (we may guess), so countless that only He who has created all things in number can enumerate them, the whole cosmos suffers a triple contraction in its downward fourfold progress…"
- Cardinal Nicholas of Cusa (1401 –1464)
