Hi Petaurista

To take your three questions in turn:

Research in medical sciences:
Not being a medic myself, I am not fully qualified to answer this, and I shall make enquiries and report back.
My layman's view would be to say NO, but only in the context of a narrow definition of "Western" medical science conducted in laboratories.
What original research he would have had to conduct to adapt what he had learnt in Strassbourg to the conditions in which he was working will hardly have been scientifically recorded. But I shall enquire!

Exploring the natural world and working for environmental preservation:
For me, the most telling record of his love and appreciation of nature was found in his letters to his wife before they were married,(now published by Syracuse University Press under the title The Albert Schweitzer-Helene Bresslau Letters 1902-1012, and well worth reading for many reasons).
However, it speaks out of nearly all his writings.

He was in awe of Nature ( the dictionary translation of the key words of his philosophy - "Ehrfurcht vor dem Leben" is "to be in awe of life", - normally translated as "Reverence for Life") and this awe pervades all his writings.
From my personal experience of my time with him in 1962/63 he showed little interest in an academic or touristic exploration, but where it impacted on his work he was meticulous and most thorough in his investigations. He knew every quality of every timber and every tree in the forests that surrounded him and his concern was as much for the welfare of plants in his environment, ( and everywhere ) as it was for animals.

There were large trees in the central space of his hospital village. Due to the frequent foot traffic beneath them the ground became eroded. He gave instruction - to me, as I was the foreman of his work team at the time, - to transport earth from an excavation that was in progress, to be deposited on the roots of these trees.
After a couple of days of this, he decided, that the quality of the earth was not good for the trees and he had it all removed and had other earth brought in.

This incident taught me many things about this man: He was not infallible. He was not too proud to admit a mistake. The wellbeing of the trees was more important to him than the pragmatic and economic aspects of making use of earth that was in any case being excavated. He remained good humoured throughout the affair.

Environmental preservation was not a term in common usage at the time. But as you say, he was an inspiration to Rachel Carson who then allerted a wide public to this concept. To Schweitzer that was just business as usual.

Was he cheerful and playfull or serious and formal:
Applied to Schweitzer I would not see this as an either/or situation. If you have seen the famous photographs of him with his pelican, you will have seen him having fun, - and that was a dayly occurance. He often had fun, - for instance - cheerfully and playfully picking an argument with a reporter, of whom there were a great many. ( Some lacked a sense of humour and did not cope well with that). When he was asked, whether he would have any objections to a dancing party in one of the rooms, he said he would, unless he ws invited and could contribute the wine, ( he was 88 at the time).

But there were other times. I do not ever remember him being what I would call 'formal,' however, 'serious' was another matter. When you wanted to ask him something or discuss something with him, you had his full attention and that was serious. I was a young man then and to me it felt like being drawn into the present moment with full focus of attention, - a kind of expansion of the mind. That was serious.

I thought I would try and answer from personal experience rather than quoting from his written work, which is of course awailable on the bookshelves.
I hope it is helpful and I will come back on the question of research.

Hi Petaurista,

Was he cheerful and playful?

Yes, you can see the photograph of him taken by Erika Anderson on  page 105 of the book  "Albert Schweitzer's Gift of Friendship".  You can see  a lively sense of humor.

http://www.albertschweitzer.org.uk/yabbfiles/Templates/Forum//default/smiley.gif...