Recognized for pioneering contributions in cardiology, pediatrics, obstetrics and balneotherapy, he was also an early speaker for public health and social medicine, as well as an educational theorist and textbook author.

Criticized by his adversaries at Junimea society for his accumulation of offices, and for collecting a large salary as curator of Sfântul Spiridon Hospital, Fătu nevertheless donated most of his money to the Academy.

Though largely forgotten within two generations, Fătu survived in cultural memory as a partial inspiration for Zaharia Trahanache, a ridiculous but ultimately likeable figure in Ion Luca Caragiale's political comedy, O scrisoare pierdută.

As noted by historian A. D. Xenopol, Moldavian Prince Mihail Sturdza and his adviser Gheorghe Asachi were tacitly encouraging "people from the lower strata of society" to acquire and education, and then to take up employment in the state apparatus, at the expense of boyardom.

[8] From 1834, one of six Moldavians to have qualified for a scholarship from the banker-philanthropist Hagi Constantin Popp,[9] Fătu was sent abroad, on condition that, upon graduating, he would return the favor by teaching a public "course in philosophy, law and political economy".

[15] His friends at home included fellow naturalist Ion Ionescu de la Brad, who noted admiringly that Fătu was "enamored with his studies", and an inspiration to the other Moldavians.

[20] In 1850, Fătu contributed a monograph on the prevention of malaria; he also focused his activity on obstretics, balneotherapy and dietetics, with Învățătură dietetică relativă la scrofule ("A Dietary Instruction against Scrofulae"), followed by Descrierea și întrebuințarea apeĭ simple și a apelor minerale din Moldova ("Description and Use of Plain and Mineral Water in Moldavia", 1851) and Manualu pentru învățĕtura móșelor ("A Textbook of Midwife Instructions", 1852).

[21] At the time, he insisted, against religious observance and popular superstition, that women wash themselves as often as possible; he also began advocating a government-sponsored program of spa tourism, but his proposal was casually ignored.

[7][26] Fătu also created the Society for the Encouragement of Young Romanians to Study Abroad on March 22, 1855, providing it with a capital of 1,000 ducats from his own estate,[27] and publishing its statutes as a brochure.

[29] When the Crimean War toppled the Regulamentul Organic regime, placing the Danubian Principalities under the shared tutelage of Great Powers, Aga Fătu became marginally involved in the liberal and Romanian nationalist movement.

[33] The new chambers inaugurated a process whereby Fătu's Paris friend and National-Party favorite, Cuza, was elected the new prince of Moldavia—and then as Domnitor of the United Principalities (the basis for modern Romania).

[35] The same text pioneered medical jurisprudence, including the basics of mental health law and forensic science,[36] sketched out food safety codes, regulated the creation of public toilets, and standardized the depth of graves.

[38] As social historian Constanța Vintilă-Ghițulescu remarks, Fătu's law integrated well within the "hygienist wave" of "civilized Europe", with doctors emerging as "key figures in the construction of the modern state.

"[39] However, according to fellow hygienist Iacob Felix, the project was simply ignored by the government of Nicolae Crețulescu, and the Assembly of Deputies consulted it only for laws establishing county councils.

In Moldavia in particular, the central issue dividing society was that of Jewish emancipation: Factionalists, motivated by economic antisemitism, opposed the integration of Romanian Jews, whereas conservatives supported it.

The clampdown by the authorities resulted in the temporary arrest of various Factionalists and allies: Fătu was picked up alongside Vasile Gheorghian, Alexandru Gheorghiu, Alecu D. Holban and Petru Poni.

[52] Indirectly responsible for the fall of the Ștefan Golescu cabinet and a rift between the "Reds" and the Faction, this proposed legislation was at the center of an international scandal—not just because it discriminated against Jews, but also because it was retroactive in nature.

[56] Taking up medical teaching at Socola Monastery seminary in 1869,[57] by 1870 Fătu was editing the country's most prestigious research journal, Revista Șciințifică, with C. F. Robescu and Grigoriu Ștefănescu as fellow directors.

Reviewing the work in Revista Șciințifică, agronomist Petre S. Aurelian recorded as a "calamity" news that Fătu had been sacked from the seminary, by order of Christian Tell, the Education Minister in Dimitrie Ghica's "White" cabinet.

[62] His inaugural address, received for the Academy by Urechia and published in 1873, was titled Încercările pentru dezvoltarea sciintielorŭ naturale în România ("Attempts to Develop Natural Sciences in Romania").

Partly in order to remedy this, in August 1872, Fătu donated 10,000 "new lei" for the creation of his eponymous fund, with prizes going to Romania's best scientific cartography, and also the entire collection of Revista Științifică.

[74] Moreover, Fătu and Petru Poni insisted on sponsoring a meteorological sub-section, which became operational in September 1874 and employed Ionescu de la Brad as one of the main surveyors.

[79] In late May 1873, Fătu and other Factionalists (including Poni, Scarlat Pastia, Dimitrie Tacu, and Ștefan C. Șendrea) participated in agitation against the regime of Domnitor Carol I by organizing Cuza's ostentatious funeral at Ruginoasa.

[86] In his last years of activity, alongside Carol Davila, Fătu also contributed greatly to the consolidation of a Iași public Medical Faculty—nucleus of the Grigore T. Popa University of Medicine and Pharmacy.

According to a 1915 memoir by journalist George Panu, who had heard the play on its first reading, the timid and congenial character Zaharia Trahanache was inspired by Fătu; the latter had drawn Caragiale's mockery when, during one National Liberal meeting he presided at Iași, he had asked his colleagues to evacuate a rowdy drunk with the words: vă rog, onorabililor, dați afară pe stimabilul!

[88] Literary historian Șerban Cioculescu believes that the reality is more complex: "If [Fătu's] way of presiding upon sessions and some of his verbal tics have indeed inspired certain lines of Caragiale's comedy, they are not actually among Trahanache's main character traits, making him an original creation.

[91] By March 1892, Ecaterina Fătu and her two minor children had also lost ownership of the family estate in Drăgușeni, Dorohoi County, as Anastasie had died without reimbursing a credit worth 200,000 lei.