Bernstein and de le Roi state:
Mossa, Nathaniel Immanuel, gives the following particulars of himself:—”I was born on October 29th, 1833, at Friedland, near Beskow. My father was a Jewish merchant, first in that town, and later in Spandau, where I passed my boyhood. When I had completed my studies at the Werder Gymnasium in Berlin I entered the University in order to study medicine. I graduated in 1858, and the next year passed the State Examination. I then entered the army for one year as a volunteer doctor, and was sent to Spandau, and then to Jüterberg.
Here, in the hospitable house of Dr. Gross (later in Barmen), I learned Hahnemann’s method of treatment. After having finished my military year’s practice, I settled in Bromberg, and soon found a promising sphere of activity. This, however, was interrupted by my participating in the military expeditions of 1864 and 1866. Also in 1870 I was called to serve in the army as physician, and took part in the siege of Strassburg, and likewise of Belfort, and returned home with the decoration of the Iron Cross.
I then renewed my medical work at Bromberg, and continued it for twenty years, and was also a contributor to the ‘General Homœopathic Periodical.’ Owing to the precarious health of my only child, I  was at length obliged to exchange the northern cold climate for that of the south, and hence settled in 1883 at Stuttgart. In 1894, in addition to my medical work, I undertook in 1894 the editorship of the above-named journal. I have also for some years acted as President of the Committee of the Society of Homœopathic Physicians at Würtemberg.
“doughty pioneer of Homoeopathy in Europe, Dr. Mossa”
“As for the story of my spiritual life, I may say, with all humility, that our gracious Lord favoured me early in my youth. Already as a school-boy I had the opportunity of learning the Gospel, since the Bible was our book for reading in my first Christian school. I was at that time much attracted by the works and utterances of Jesus, and deeply touched by His death, and impressions perseveringly strong were made upon my mind. The instruction and earnest converse I had with two fellow-workers of the British Society, Dr. Koppel and Dr. Fürst, helped me.”
This short extract from his autobiography is supplemented by the information supplied by Pastor de le Roi concerning him:—
“One day a Jewish Rabbi of his town asked him to give an address to Jewish prisoners, and he took for his text: ‘Seek ye the Lord while He is to be found, call ye upon Him while He is near,’ and he illustrated the text by the example of the prodigal son. This was the turning point in his life. He himself began to seek Him until He found Him or was found by Him. He afterwards went to  Bromberg, where he heard Koppel giving an exposition on Isa. liii. and he joined in his labours as a doctor in the Institution at Salem.Koppel recommended him for baptism to the L.J.S. missionary Bellson, in Berlin. Later in life he settled in Stuttgart, where he was a great comfort and support to Gottheil, and after his death, he himself acted as missionary of the British Society there till he was called home.”
Thank you Lord for the life of Dr Mossa, a man of faith and of science. May his service be pleasing in your sight, both as an evangelist among our people, and as a pioneer in a field of medicine and alternative therapies. Lord, who knows the effects of our lives on others and in your kingdom? Only you have an eternal perspective on the realities of our lives. May your kingdom come and your will be done, even in the small span of time you have alloted to us. Strengthen, we pray, the works of our hands, and may our lips and lives speak of your glory to others. In our Messiah’s name, Amen.
https://archive.org/stream/pathicreco19inte/pathicreco19inte_djvu.txt (search for ‘Mossa’)
Research questions – Does anyone have a photo of Dr Mossa or know what happened to his family?