Music samples are available on the accompanying playlist so turn on your volume if you would like to hear them. I invite you to open up your mind if you think classical music is boring or too complex or anything like that. The music of the past is the foundation of most of what you listen to today. When you learn about the music and the composers and the eras in which they lived, you enter a time machine that will take you to magical amazing places. Let go and let the music fill you and lift your soul.
My omissions from my previous lists were nothing compared to this present list. Here I am condensing a list of twelve favorites from a field of potential considerations spanning 400 years worth of great (the greatest?) music--how in all fairness does one do that?
Even to confine into a single genre of music labeled as "classical" multiples of different types of music makes no logical sense. In reality this list should be broken down into favorites of Baroque, classical, romantic, impressionistic, and all the various other subcategories, including 20th century music which diverges off into realms such as atonal, neo-classical, electronic, and others. To compare Mozart with John Cage is like comparing do-wop to heavy metal--they just don't fit in the same lists.
With that being said, in my list I have tried to cover the spectrum of music from the Baroque period up to the mid-nineteenth century. In compiling this list I have had to bypass many subcategories of musical styles that are placed under the broad umbrella of "classical" music as we would see for example in your local music store. I have also blatantly passed over many great composers in order to come up with twelve favorite pieces of music. These are not necessarily the greatest, but twelve that I enjoy listening to or that have particularly shaped my listening over my many years of enjoying classical music.
My Timeless Twelve Classical Favorites:
Antonio Lucio Vivaldi (March 4, 1678 – July 28, 1741) -- The Four Seasons Concerto is one of the most popular pieces of music of all time and for good reason. This is music of the Baroque Period. The amazing complexity of notes, instrumental parts, and rhythms result in a work of simple, but soaring beauty. The concerto musically depicts each of the seasons of the year. This is definitely a timeless musical treasure. 
Johann Sebastian Bach (March 21, 1685 – July 28, 1750) -- Brandenburg Concerto No. 5 is my favorite of the series of six like named concerti. I particularly like the driving sound of the harpsichord in this one, especially in the first movement where the keyboard verges on either musical madness or the voice of the powers of heaven. I often think of Bach as one of the greatest mathematicians, although his formulas have been written as some of the most incredibly intricate and beautiful musical sounds of all time. Fortunately, recordings of the Brandenburg concerti often come as a complete set so you can usually get all of them in one purchase. I am convinced, and studies have suggested, that listening to J.S. Bach will make you more intelligent. I highly recommend this music as background music for writing. Bach's music is in the Baroque style.
Ludwig van Beethoven (December 17, 1770 – March 26, 1827) -- Symphony #7 is my sentimental favorite, but Symphony #9 is arguably his greatest. One thing for certain is that every Beethoven symphony is great and if he had written only one of any of them, Beethoven would still be recognized as a great composer. I personally have an affinity for his orchestral works, but Beethoven also left a legacy of great piano and small ensemble music. Beethoven's music is in the classical tradition, but falls into the transitional period that leads up to the Romantic Period. Beethoven set a standard for composers who were to follow. His music seems to capture the angst and ultimate triumph of the human spirit. 
Franz Schubert (January 31, 1797 – November 19, 1828)-- Piano Trio in E Flat Major D929 is definitely high on my list of Schubert favorites, but his string quartets and quintets could also fit the bill. Schubert is probably my favorite composer overall. Considering he died before his 32nd birthday he was amazingly prolific having written around 600 songs, not to mention all of his keyboard, ensemble, orchestral, and other works of music. Like Beethoven, Schubert's work falls into the Post-Classical period and begins the age of Romantic Music. What could this incredible composer have accomplished if his life could have been longer?
Johannes Brahms (7 May 1833 – 3 April 1897) -- Symphony #4 is my long-standing favorite of the symphonies of this Romantic composer. I first became familiar with this during my college days in the early 1970s. The music still stirs me when I hear it, although now having heard the other symphonies of Brahms I enjoy all of them. He also wrote many other fine pieces of music.
Camille Saint-Saëns (October 9, 1835 – December 16, 1921)-- Symphony #3 "Organ Symphony" is the amazing work of music that leads me to Saint-Saens. He is probably most well known for his "Carnival of the Animals", which I have been well familiar with since childhood. I discovered the stirring "Organ Symphony" when I was in college. This is an exciting piece of music with moments of great beauty. Then when the pipe organ kicks in, I am lifted to another plane of listening. I also like the Piano Concertos of Saint-Saens. His style is greatly influenced by the Classical Era but also falls in the Romantic style and begins the Impressionistic Era. 
Claude Debussy (August 22, 1862 – March 25, 1918) -- Prelude à L'après-midi d'un faune (Prelude to The Afternoon of a Faun) is one of my Debussy favorites, although many of his works could be interchanged with this work. Debussy composed in the dreamy, shimmering style known as impressionism. On the surface Prelude and many of Debussy's other works seem slow, boring, and perhaps even depressing. However I am amazed when listen closely to Debussy's compositions. I wonder how did he ever think of music that would sound so beautiful. If there was ever music to recreate your thoughts on a dreamy lazy day Prelude does that. It is music that is introspective and relaxing. 
Erik Satie (May 17, 1866 – July 1, 1925) --- Trois Gymnopédies is the music that really inspired me to explore classical music in 1969. Public television had shown a documentary about Impressionistic/Avant-garde French composer Erik Satie. When I heard the Trois Gynmopedies I knew I must find out more. Satie primarily wrote short piano pieces. His catalog of music is not real extensive, but the Gymnopedies are all I need from him.
Béla Bartók (March 25, 1881 – September 26, 1945) --The Six String Quartets does not grab me melodically, but stylistically it is an incredible piece of modern music. Often harsh, tense, angry, and introspective this is music of the modern age. A forerunner to progressive rock music except this is done string quartet style. Bartok composes new sounds for the string quartet that gives the ensemble new depth. This could easily be music that could be used for a movie soundtrack. 
Igor Stravinsky (June 17, 1882 – April 6, 1971) -- The Rite of Spring was so radically different at the time of its release that its premiere in Paris nearly turned into a riot. People at the time did not understand this music. Now it doesn't sound so uncommon, but it still sounds incredible with its perscussiveness and chaotic orchestral sounds. This is music that seems to foreshadow the coming ages of jazz and rock and roll.
Ralph Vaughan Williams (October 12, 1872 - August 26, 1958) -- Symphony #7 (Sinfonia Antarctica) was originally based on a filmscore Vaughn Williams had written. When I first heard this back in my college days I immediately fell in love with this symphony. It has the grand organ, crystalline sounding xylophone, piano, choral voices, and, best of all, a wind machine. When I listen to this I can visualize a ship sailing amongst the ice bergs and frigidity of the Antarctic desolation. It is incredible modern music that fits in the tradition of film scoring.I have left out many great composers and works. Make sure you visit the other participants' sites to see what other classical music is beloved and appreciated. And then, try to make an effort to seek out some of this music yourself. If you allow yourself to let the music in, you will be taken to some of the most wondrous places that human imagination has ever created. Beethoven is attributed to saying that "Music is the language of God." When I listen to classical music I can easily believe that.
