He was a true scholar, a scholar worthy of deep respect, and a senior mentor devoted to teaching and nurturing younger generations.
他是一位真正的學者，一位令人敬重的學者；更是一位用心教導、提攜後輩的長者。

Ching-Shui was a young Assistant Professor when I entered UC Berkeley Stat Dept as a graduate student. I still remember how my fellow students and I encouraged one another to work hard by recalling Ching-Shui’s dedication to research. One story that circulated among us was that he would place three chairs together to make a makeshift bed, take a brief nap to regain his energy, and then return to his research.
Ching-Shui will be remembered not just for his outstanding research, but also for his remarkable character and great integrity.
To me, he will always be more than a teacher. He was a mentor, a friend, and, above all, a truly great human being.

敬愛的鄭老師是溫暖而堅定的長者，一位默默令人敬重的學者與師長。
2004年8月，我在中研院擔任研習生，為申請美國博士班做準備。那段短短一年間，鄭老師成了我心中的楷模。每場seminar鄭老師都親力參與，儘管坐在後方的我大多似懂非懂，但也因此對統計學的廣度有了更深的認識。
後來我很幸運地進入Penn State攻讀統計博士。有次在學術活動中，我向鄭老師訴說：「Penn State好無聊啊！」鄭老師只是笑笑地回答：「那就多讀書呀。」這句話看似簡單，卻成了我在求學期間的提醒——專注於學問本身，而非外在環境。
這些年來，雖然交流的機會不多，但每次與鄭老師的互動，都讓我感受到他那份對年輕學者的默默支持與堅定期許。

Professor Cheng was my PhD thesis external examiner. I read many of his papers. His work is always so deep. We met and chatted many times in the conferences. He is very kind, wise, knowledgeable, humble and approachable. He is truly a role model for scholars and researchers. I am forever grateful for his help along the way in my academic journey. It is deeply sad to lose him. Rest in peace!

I am deeply sad to hear the news. Ching-Shui is a terrific scholar and has always kindly shared professional advice when asked. His passing is a great loss to our field. Best wishes and my deepest condolences to his family.

Prof. Cheng was the chair of the Institute of Statistical Science when I first joined Academia Sinica. I will always be grateful for his kindness, support, and guidance over the years. I was deeply saddened and shocked to hear of his passing. May he rest in peace.

Dear Ching-Shui, You have set up a role model for us to conduct academic research deeply with new innovation and rigorous steps. At the same time, you are also generous to provide wise advice for us regarding academic research, career development and life experience. We missed those invaluable opportunities to learn from you for the past years!
Truly,
Henry and Sunny

鄭清水院士是溫暖謙和的老師,凡事親力親為,是我學習歷程中的楷模,在此以沉痛與敬仰的心情追思他的離去。

追思鄭院士：一位溫和、正直而良善的長者
我與鄭院士是同一年（2003年）加入統計所，那年是他第一次擔任統計所所長。那時候，同仁們的辦公室都還集中在所內，相對容易在交誼廳偶遇。大家見了面聊聊天，有時候會談得興高采烈。他一直很關心我們，有幾次聊完準備離開時，他總會微笑著對我說：「多花時間寫你的論文。」
2013年，鄭所長回任所長。有一次，我聽說他健檢有「三高」的問題。當時我大發熱心，特地做了麥片粥裝在一個小盒子裡帶給他，還特別囑咐他一定要吃，他笑笑地答應了。那天剛好有一個會議，他提著那個小盒子，一路上被幾位同仁調侃，但還是吃完了那小盒麥片。他尊重這盒麥片粥背後的善意，而不在意隨之而來的尷尬。那一刻，我深深覺得他是一個既慈祥又有智慧的長者。
三年前，他回中研院訪問，我特別去主婦聯盟買了相對健康的年節零食送給他。我說：「讓您的孫子嚐嚐台灣過年的零食！」他卻幽默地回答：「這麼好吃的零食，我要自己吃！」他就是這樣一個很可愛、很溫暖、又很會鼓勵人的長輩。
他的學術成就眾所皆知，當選院士更是眾望所歸。我有幾位好朋友曾在柏克萊與鄭院士共事過，無論在學術造詣或待人接物上，都對他推崇備至。他是一個表裡如一、始終一致的人。
去年底在中研院的會議上，是我與鄭院士最後一次見面。他當時看起來精神矍鑠。週一聽到風順告訴我鄭院士離世的消息，我心中充滿了錯愕、不捨與感傷。一方面，慶幸他沒有被病痛折磨太久；另一方面，也為我們失去了一位溫和、正直、良善的長者而感到深深的遺憾。
願鄭院士夫人以及女兒一家人保重，節哀

I learned of Ching-Shui the first day when I entered Tsing-Hua in 1970. My respect for him grew dramatically even since. He was a true scholar, a caring person, and a wonderful human being. His impacts on our profession far exceed his outstanding research achievements. With his passing, I lost a dear friend and a role model. RIP.

Ching-Shui is not just a mentor and a collaborator to me, he is a dear friend of mine.

We were all 1972 graduates at National Tsing Hua University. Prof. Cheng is a very talented and smart person. When I was still studying Materials Science and Engineering at Northwestern University, he has already come for a faculty position interview. We met at Holiday Inn, Downtown Evanston, Illinois, which might happen between 1977 and 1978.
I am very sorry to hear that Prof. Cheng has passed away. We hope and pray that he passed away without suffering. We have been praying for his family. Our deepest condolences!

Because my home town was Hsinchu, I got to know the “famous” 郑清水at Tsinghua Math, during my frequent visits to the Tsinghua campus. I went to Berkeley in 1973 and he went to Cornell in 1974. We were in the same job market in 1977 and our research topics was experimental design, what a coincidence and fate! We published our thesis work in AoS in 1978. His two papers appeared on pp. 1239-1272, my two papers on pp. 1273-1301. The four papers appeared back-to-back in a top journal. We knew it was a “coincidence” arranged by our friend and mentor Sam Hedayat (who, we believe, handled the reviews). It signals our long-term friendship. We only wrote one joint paper (AoS 1981) but collaborated on bigger things. I was the second Editor of Statistica Sinica and he was the third. (George Tiao, whom we all admired, was the founding Editor.) Several of my top students call him uncle “师叔“。
Last year he told me about the treatment he was going thru. The signs were good. He looked well this February. I could not believe he suddenly left us. May you rest in peace in heaven.

能認識鄭清水老師，是我這輩子非常非常幸運的事。從 2010 年在清華統計所求學時，聽鄭老師的暑期課程開始，我就深受他嚴謹的學術態度影響。後來，2013 年鄭老師回到中研院統計所擔任所長，仍記得當年曾答應讓我跟他做研究，並給我機會成為他的獎補助生。這些年來，我曾數次向鄭老師表達感謝，他卻總是要我不要想太多，並說：「這就是緣分。」我多麼希望這份緣分能一直延續下去。鄭老師，謝謝您，這是我心中非常珍惜、感恩，也永遠懷念的一段過去。

初中、高中同校時，我就已久聞鄭清水是學霸。他在全校的模擬考試常名列前茅，我只能遠而敬之。 大學聯考放榜後，才發現他以系榜首進清華大學數學系，我有緣和他同班。他的分數原可選擇任何熱門科系，因清華數學系教授編寫高中新數學教科書，設置東華書局數學獎學金的鼓勵，他以清華數學系為第一志願，足見其對數學的熱愛與志向。多年後他首次回國講學，決定回到母校統計所擔任一年的研究講座，終於實現回饋母校的心願。 大一結束後，不少同學因數學過於抽象而萌生退意，轉系或休學重考。阿水與陳鞏、黃景彰三位同學主動利用暑假義務講授，為同學預習大二必修的高等微積分、高等幾何及高等代數，鼓勵大家繼續一起前行。他們站在講臺上的風采，至今仍歷歷在目，也讓我對阿水有了「亦師亦友」的深刻感受。 赴美求學後，我們又不約而同進入統計學領域。1977年阿水取得康乃爾大學博士學位，任教於 UC Berkeley；我則轉到 Stanford 統計系博士班。他是實驗設計的理論學家，我對生物醫學統計有興趣；從數學到統計，我雖與他較近卻更敬之。 畢業後，我在美國工作兩年多，回到中央研究院統計學研究所工作。後來李遠哲教授自UC Berkeley 回國榮任本院院長，他延攬多位卓越人才來院服務。在李院長努力下，阿水於2003年返國擔任本院統計所首位特聘研究員兼所長。他不僅引領國內實驗設計研究持續發展，更積極培育年輕學者，鼓勵年輕同仁首次申請到院內群體計畫，首聘研究技師人員，推動跨領域合作與國際交流。 當時本所幾位同仁積極投入跨領域的生物資訊研究，鄭所長特別編定預算，主辦2004 Taipei Symposium on Statistical Genomics。研討會也舉行壁報論文競賽，由與會的國際知名學者評審，包括英語問答。楊欣洲博士當年在本院生物醫學研究所服國防役，參加競賽，拔得頭籌，鄭所長於閉幕式頒發競賽冠軍的大紅包給他。欣洲老師現任本所所長，撫今追昔，深感鄭所長薪傳力量的啟發，而推進國內統計界跨領域合作研究的起飛。 阿水後來再度回到本所擔任所長，更鼓舞同仁推廣研究成果，每年都有同仁申請到前瞻計畫與深耕計畫，以及推動院校際資料科學學程。以其國際學術地位，他展現遠見、開放胸襟，提昇了臺灣統計界更邁向國際發展。夫人士澤也熱心的每週為所內研習生和研究助理主持英語座談會，自由討論生活藝術及職涯規劃等，開拓年輕人的國際視野，他們受惠至深，獲得成長與發展的契機。 阿水當選中央研究院院士，實至名歸，大家都敬佩他的學術成就，而我更難忘的是他的為人處事。他自中學時期便展現謙和沉穩與領導風範；除了數理專長外，對人文、藝術、歷史、地理亦廣泛涉獵，見識淵博。大學班友群組中，他的文章總旁徵博引、發人深省，也流露出對社會公益與公平正義的關懷。 阿水與士澤熱愛旅行，喜歡搭遊輪遨遊四海，常分享世界各地的見聞與攝影作品，他樂於娓娓道來相關的人文典故。他們夫妻鶼鰈情深，生活充滿智慧與品味，令人欣羨。 阿水遠行而去，已無病無痛，在天堂與先行故友暢談統計科學，關心我們資料科學的發展與國際合作。追思感念他對學術界與後輩的深遠影響，更懷念這位亦師亦友的老同學、老同事。 祈禱士澤、妞妞及家人平安順遂。

When I was a research assistant at Academia Sinica, I often heard Professor Ming-Chung Chang speak about Professor Ching-Shui Cheng with deep gratitude and respect. Through Professor Chang’s stories, I came to understand Professor Cheng’s rigorous scholarship and the lasting influence he had on his students and younger scholars. His influence on Professor Chang has also reached me in a quiet but meaningful way. I remember Professor Cheng with sincere gratitude and deep respect.

We will miss the talks and times we celebrated milestones together.

I last visited Ching-Shui at his home on May 16, shortly after an emergency hospital visit. Although he was in pain, he remained calm and gracious, as he always was. I did not anticipate such a rapid decline and was deeply saddened and shaken by the news of his passing.
Ching-Shui and I first met at Berkeley in 1977, a year before I entered the PhD program there. Jeff Wu was there too. I was at a pivotal point in my academic career, deciding whether to transfer to Berkeley and switch my field of study from mathematics to statistics. Ching-Shui had just arrived that year, ahead of his advisor, Jack Kiefer, who later became my PhD co-advisor (along with Lucien Le Cam after Kiefer's tragic, sudden death in 1981). He and Jeff encouraged me to take the leap, for which I am forever grateful. We became academic siblings and lifelong friends.
Ching-Shui was a true gentleman and scholar. His kindness, wisdom, and friendship enriched the lives of so many. He will be deeply missed.

2014年7月至2016年4月, 我很榮幸能在鄭老師的指導下進行博士後研究. 老師不只帶領我投入共同的研究工作, 更給予我很大的信任與自由, 鼓勵我依照自己的興趣探索想做的研究. 這份包容與支持, 對當時剛踏入學術職涯的我而言是非常珍貴的力量.
這張照片是我離職前, 與老師, 師母及明中在南港City Link 的貳樓餐廳一起聚餐時留下的合影. 如今重看照片, 心中滿是懷念與感謝. 感念老師曾經的指導, 鼓勵與照顧. 願老師安息.

再說幾句
- soft gravity of charm 悼清水
阿水的離去太太突然
阿水走了以後的那幾天, 腦中一直浮現這兩句
“輕輕的我走了, ...., 不帶走一片雲彩”
是徐自摩的再別康橋
回想起來,真是的
每回見到的阿水
笑容, 就像掛在天邊的雲彩
典雅,大方,溫馨,
無數雙眼睛
就這樣被吸進一個
飽滿溫柔的萬有引力塲
阿水的charm 內歛住 無時無刻助人為樂 的 熹悅
許多事蹟同仁們已在清水緬懐錄裏載紀
阿水帶來的助人彩雲
是他帶不走的永恆貢獻 - 助人
助統計界,助統計所
助我

讀初一時，曾在報上看到一則報導建中的數學天才，名叫鄭清水，留下深刻印象，沒想到日後有幸成為同事。清水兄於2003年到統計所擔任所長，他找了林國棟兄與我擔任副所長，我雖僅任職一年，但一直與清水兄有不少的聯繫，他對所的付出可謂是全力以赴，不論是所內的大小事物，台灣統計界的互動與積極參與，以及與國際統計界的交流，他都有許多建設性的想法與作為，在前幾任所長奠下的基礎下，他的努力進一步深化了統計所日後在多方面的發展，在他的任期裡，統計所首次成功地徵聘到外籍學者(John Aston)，而他的積極但不強勢的作風保持了所內和諧的氣氛，此外，清水兄的夫人士澤姐義務教授所內年輕助理英語會話，為他們日後出國深造做好準備。清水兄的辭世令大家不捨，願士澤姐節哀並保重身體！

在一次清大的演講中，鄭老師讓還在碩士班的我看到了實驗設計的美，啟發了我的研究之路。鄭老師的鼓勵，提攜與照顧，讓我能一路滿懷熱情地走在學術研究的道路上。 能認識鄭老師真的是一件非常幸運的事! 記得以前常常跟鄭老師說“您走路好快呀”我常在中研院側門看到老師，然後一路小跑步追趕到了統計所門口才追上老師。 鄭老師，您這次又走太快了。我們都很想念您！

鄭清水院士是我大學同班同學。 阿水在學生時就特別突出，後來的學術成就更是傑出。 他為人寬厚、誠懇、認真。記得他年輕時曾說：其實不論念什麼，做什麼，能有興致、有勁的去做最重要。曾在大二教過我們的劉政老師，從Berkeley 畢業到Cornell任教，後來生病住院，清水特地從西岸飛到東岸去看他，給他打氣。 阿水和士澤生活恬淡，有條理，有原則。經常有機會聽他們分享旅行和閱讀的觀察和見解，十分享受。最後見到阿水是去年十二月中旬，他說疾病的發現很突然，但他會試著努力與疾病共存。當6月8日我從同學羅文浩那聽到士澤傳來阿水走了的訊息，失掉這麼好的老友真是可惜，再也聽不到他智慧的分享。祈禱阿水在天上安好，士澤及家人平安。