His brother Louis-Auguste Say (1774–1840) was a director of a sugar refinery at Nantes who wrote several books on economics; his son, Horace-Émile Say (1794–1860), Léon Say's father, was educated at Geneva, before travelling in America.
[1] Léon Say was thus imbued with a zeal for economic study and theory, which first emerged at the age of twenty-two with his brief Histoire de la caisse descompte.
Meanwhile, he was a regular contributor to the Journal des débats, growing his reputation through a series of brilliant attacks on the financial administration of Baron Haussmann, Prefect of the Seine.
He was immediately chosen as rapporteur to the parliamentary commission regarding the state of French national finances, and in this capacity he produced two elaborate statements.
This was, however, a gift to Say who was eminently suited to the task; he only quit this post to assume, in December 1872, the office of Minister of Finance — a remarkable tribute to his abilities from Thiers, who held strong protectionist views.
It was at a conference held between Say, Gambetta and Charles de Freycinet in 1878 that the great scheme of public works, introduced by the latter, was adopted as government policy.
In accordance with his free-trade market principles, he believed that the surest way of enriching the French nation, and therefore its Treasury, was to remove all restrictions on internal commerce.
[1] On 30 April 1880 he accepted the post of Ambassador to London for the purpose of negotiating a commercial treaty between France and Britain, but the Presidency of the Senate having become vacant, he was elected to this office on 25 May, but not before securing an outline agreement with the British Government, an important feature of which was the reduction of duty on cheaper French wines.
Say's economic policies fell out of favour with the new generation of French politicians, since his academic Liberalism became regarded as old-fashioned; Socialism, which he never ceased to attack, obtained even greater power, and free-trade was discarded in favor of Félix Méline's protectionism, against which Say organized in vain the Ligue contre le renchérissement du pain.