The Monk Albertus Bayr discovers transmutation through evoking a spirit.

I, Frater Albertus Bayr, of the Order of the Carmelites, hereby testify before God that in the Year 1568, on the 18th of February, the Feast of the Purification of the Virgin Mary, in my Cell in the monastery of Maria Magdalena de Stella Nova, such a Countenance appeared to me and held converse with me.
I had risen and retired to bed with philosophical books and thoughts; day and night I had prayed fervently to our Lord God to reveal to me the Truth of this art.
Then, in my ignorance, and may God forgive me, I knew not what else to do. With great assiduity I had laboured in vain for three and twenty years with my abbot and by Day and by Night had diligently tended the fire. So I thought that one could learn this Mystery from no man and must wrest it from the Spirits. Yet, as, praised be God, I learned in the end, more is possible to Men than to Spirits.
So did I on that day begin with the Ceremonies and Exorcisms of Italian-Spanish monks. As the exorcist of the monastery, God forgive me, I then called the Spirit of the Planet Mercury, and demanded that it should speak and answer.
In the shape of a dark and elongated Disc, a Shadow without definite Contour, did it appear to me and in ringing and resounding Tones permit Question and Answer.
At its Bidding I sat down at the table, in order with pen and ink to record the Truth. Then the Shadow, the black Gleam, entered into the middle of the Circle. The blessed sword, the consecrated candles, and the rest of the magic, did not hold it from entering.
Slowly it changed from Black through ashen grey clouds to a bright white Gleam, and at last it was transformed from the White, through a shining yellow colour, into the most glorious Red. Form and Contours, however, changed not, and stood immovable until the end of the conversation in the Magic Circle. But in the middle of the gleam the Sign of Mercurius appeared in changing colours.
When it disappeared, my cell was lit up within and without blood-red, and it was as when the Sun appears blood-red in a room.
After this Revelation I settled everything with my Abbot, and with Labour and Diligence procured within two years eleven pounds and three and a half ounces of the right Material. Anno 1571 I had completed the Work and truly and clearly set it down. But my Abbot did not live to see it. On the Second of June preceding he was found dead in bed alongside his Concubine.
From the Beginning to the End of the Work I saw all colours, as revealed by the Spirit in the Circle. Three main colours did I find in the Work - Black, White and Red. And when a mistake occurred, I received counsel and information from the Spirit.
But after completing the Work I have not for years been able to summon the Spirit. Therefore the improvement in Quality and Quantity has been very difficult for me.
And as the other brethren and in especial the new Abbot were very hostile to me, because they could not learn the Secret from me, a few years later I went privily on my way. With my Tincture and a few ancient good Egyptian books I came safely to Augsburg. Thereafter I travelled towards Nuremberg, and rejoiced to be on German Soil.
I am consoled by the hope of soon finding one who will show to me the Improving and Increasing. May God Almighty help all in His mercy. Be He praised evermore. Amen.
-- Figulus, Benedictus. Rosarium novum Olympicum et benedictum. Das ist: ein newer gebenedeyter philosophischer Rosengarten..., Basel, 1608..

Item, I have received from an aristocratic and distinguished Nobleman this following trustworthy Report:
That in this our time an Italian monk, who had abandoned himself all too much to this acquired Art, had renounced his monastic life and order, which until then he had served, together with the Papal religion and doctrine, and had come to Germany. In order that there he might order and enjoy his life in better freedom, he had entirely rejected his monk's cowl and the strict monastery rules.
But since he showed himself less cautious than is prudent, two rogues approached him and showed themselves so affectionate, that he took them to him as his trusted friends. By whom, however, on a journey which they later undertook in company, he was criminally murdered in a wood and robbed of his life.
But one of the murderers showed the Powder which they found on the monk to many and various Princes and distinguished gentlemen, and represented it as his own. Thereby he defrauded many of a great deal.

--Theobald von Hoghelande, De Alchemiae Difficultatibus, Cologne 1594.