What the Vatican is to Roman Catholicism, Tanglewood is to Liberalism. Its open grounds, its combined love of excellence and inclusiveness, its public outreach and quiet spots, mark its mission to cultivate private genius in view of collective happiness. Saturday morning started with a stirring lecture by Michael Nock (Interim Director of the Tanglewood Music Center) on Schiller’s ode: To Joy, which he described as an “Anthem of the Enlightenment,” proposing “a set of values and principles for organizing humanity.” Will we succeed in advancing Beethoven’s project, calling for all men to be brothers? The progress of humanity towards a better and more just future, Nock concluded, depends on all of us.

Saturday’s evening concert at a packed shed extending into a lawn well populated with twinkling candles and lanterns brought a still defiantly boyish Michael Tilson Thomas on stage to conduct the BSO in a program of three subtly emblematic 20^th-century works that grapple with human progress in three distinctive ways.

The opener, Nicolai Rimsky-Korsakov’s Dubinushka, celebrates the 1905 Russian uprising that replaced autocratic rule with a constitutional monarchy. Tilson Thomas gave it a clear, crisp reading – a palpable “dawn of a new day” power, full of joyous hope and determination. What will an enlightened humanity bring about?

Sergey Rachmaninoff’s struggle with modernism was less political, more private and deeply versed in the phenomena of personal depression and resilience. No piece embodies his acquaintance with psychic suffering and survival better than his Third Piano Concerto, composed in 1909 and first performed in the New World, in New York City. Well known for its difficulty, the work remained unpopular for many years, until Vladimir Horowitz brought it into the mainstream. Now almost every concert pianist plays it, and performance styles show a large range of variation, from thunderously visceral to lyrical and understated.

Alexander Malofeev, with his prodigious technical ability coupled with subtlety and depth of interpretation, gave us both technical brilliance and lyrical expressivity. Tilson Thomas and Malofeev opened with a quiet, soft statement of the first theme, rising in power with the ensuing piano arpeggios. This foreshadowed the central feature of Malofeev’s performance, namely that strong emotions, barely held under control, suddenly erupted in uncontainable manic outbursts. Part of Malofeev’s effectiveness lay in the effort to resist the temptation to interpret the emotions. He conveyed their menacing unfamiliarity, their explosive novelty that escape labeling and recognition. He unveiled the “stranger within” who torments us and shackles our inner drive without reprieve or possibility of reasonable dialogue.

Is the adagio a commemoration and working through of Rachmaninoff’s own depression and eventual return to composition? Malofeev cast the famous piano entry as an expressive chaos of affect; the orchestra answered with hopeful uplift. With or without psychoanalysis, the movement spoke of a tragedy that found its resolution at last in a suddenly light-spirited and dizzying final variation. Palpable relief and excitement in the transition led to the Finale, which came across with total abandon to joy: arpeggios ripped from the keyboard, rapturous crescendos, recovered vitality pouring out and overflowing. Sections that can sound sickly sweet here felt passionate. The astonishing speed of Malofeev’s fingerwork portrayed psychic release as quasi-miraculous — unhoped-for and undeserved.

Responding to the audience’s volcanic eruption of delight, Malofeev treated us to Pletnev’s delicate transcription of the Pas de Deux from Tchaikovsky’s The Nutcracker. His soothing, reassuring, and charming interpretation reminded us not to overlook hidden gems of our musical patrimony because of prejudice. Liberalism does not set fire to the past (Cf Shostakovich’s May Day Symphony chorale), but rather nurtures it through constant revision and rediscovery.

If Rachmaninoff (mon semblable, mon frère) redirects the heroism of late Romanticism to grapple with the revelation of unconscious forces within us, Aaron Copland returns to the point of departure: Alle menschen werden Brüder. Composed in Mexico (First movement), New Jersey (Second movement), Connecticut (Third movement) and to some extent at Tanglewood (Fourth movement), Copland’s Third Symphony is deeply hermetic. Under a surface accessibility —reprise of Fanfare for the Common Man — it hides a massive trove of questions and experimental new departures. Tilson Thomas, who worked in his youth with Copland, unlocked much of this difficult material. He emphasized timbre and texture throughout, which gave the piece a vitality that recordings typically lack. Copland wrote this Third Symphony for a live performance before a living audience in a universe teeming with life. In the first movement, Tilson Thomas outlined the three successive modal themes with a welcome clarity that expanded a sense of sunrise to a planetary scale. In particular, he exploited the trombone and the xylophone to create a Holst-like cosmic home for us, full of new promises and challenges.

Tilson Thomas gave the ensuing Scherzo a raucous, brash reading, evoking industrial and urban acoustics, where we risk falling into a purposefulness without purpose. On this reading, the third movement Andantino, starting with a very pure and anguished singular voice in the first violins, grapples with isolation, loss, grief, and the pain of deadening work routines and unacknowledged personal despair. In Tilson Thomas’s subtle rendering, activity seemed to blossom slowly into inventiveness, implying that rather than falling back into Romanticism and clinging to dreams of past glory in order to assuage a sense of personal emptiness, modern man will craft new selves.

With determination and resolve, the fanfare returned in the final movement with timpani and drums. Tilson Thomas gave it an alluring seriousness. Even as the fanfare pervaded the whole, he made sure that we heard tender, quirky individual instruments joining in the cacophony and waltz-like march freely and joyously, on their own terms and with their own color. The very notion of “common man” beautifully diversified into an array of colors and pitches, tones and outlooks. Rainbow-like, inclusive: Alle Lebewesen werden Brüder (und Schwestern). Responding to the audience’s ovation, Tilson Thomas held up the score and pointed to it, plainly saying that the applause belonged to Copland.

Leon Golub is an astrophysicist at the Center for Astrophysics in Cambridge and has been a lover of classical music for over 50 years.