米兰•昆德拉的小说《不能承受的生命之轻》，其中诸多万花筒般的哲理性问题好象给我们摆了一个八卦阵，设置了一个迷宫。小说还提出了众多的范畴：同情与背叛、性友谊、媚俗和粪便、共产主义，灵与肉、轻与重……就更令人眩目。所以对小说人人都有自己的理解，各人的解释也是众说纷纭，见仁见智。
我仅就其“轻与重”谈谈个人理解。
人们常常感叹的是不能承受的生命之重，作家反过来说，这就进入了深层：人生就是履行责任背负重担，人人都有不能承受的生命之重。“最沉重的负担同时也成了最强盛的生命力的影像。负担越重，我们的生命越贴近大地，它就越真切实在。”；而当我们不去背负重担的时候，这种没有任何责任和负担的轻松就是生命的空虚和空白了。作为人，这种轻松当然就是比沉重更不能承受的。“当负担完全缺失，人就会变得比空气还轻，就会飘起来，就会远离大地和地上的生命，人也就只是一个半真的存在，其运动也会变得自由而没有意义。”多少名人也都说过类似的话：人最不能忍受的就是空虚。
“那么，到底选择什么？是重还是轻？”不言自明。
个人的理解，小说的主人公特蕾莎是一个生命之重的人物。对爱情的专注和责任、对丈夫的宽容和忍受、对事业的认真和执着、对善恶的爱憎和明断……，在重压之下艰难地活着，活得实在。以至在这个没有美和真爱的人间，最后只能在一条狗的身上找到人间的牧歌、找到真爱。正如萨比娜所说：“美就是被背弃的世界。”既使在这种情况下，特蕾莎还在怀着内疚的心情检讨自己是否对托马斯太苛刻？这就是她人生的境界。始终恪守人生的戒尺！这也是她这个“被背弃的世界”的美之所在。虽然特蕾莎也有过一次对托马斯的越轨报复行为，但“与工程师的小插曲是否让她已经明白，风流韵事与爱情毫不相干？是否明白风流之轻松，了无重负？如今她是不是比较心静了？根本不是。”于是她立即又回到了她的严肃人生的道德的轨道上。与之相反，托马斯、弗兰茨、萨比娜则是生命之轻的一类人物。是一些飘浮在半空的人物，没有任何责任和约束的规范。托马斯的情人有两百多，还为此托词说性与爱毫不相干，其乱性到无以复加的地步，甚至连自己的儿子也不想认；萨比娜也是一个我行我素、随心所欲的人物，想干什么就干什么。但“你可以背叛亲人、配偶、爱情主祖国，然而当亲人、丈夫、爱情和祖国一样也不剩，还有什么好背叛的？萨比娜感觉自己周围一片空虚。这空虚是否就是一切背叛的终级？” “可说到底，萨比娜身上发生过什么事？什么也没发生。……她的悲剧不是因为重，而是在于轻。压倒她的不是重，而是不能承受的生命之轻。”
但托马斯在俄狄浦斯事件中又表现出他的生命之重的一面。表现出他对社会还有一点正义感。正是因为这一点正义感也才能表现出生命之重。也说明生命之重是与责任联系在一起的。有责才有任，有任才有重。
可以看出小说的主旨应该是明显的，是对人类生命之轻的指责和否定！个人理解是一部哲理性社会问题小说。
对于小说中大量的乱性描写，从个人感情来说我是不能接受的！但这确实也是对当今这个没落世界真实典型的描写。这种“生命之轻”也正是没落的典型。联想到贾平凹的《废都》、余华的《兄弟》，以及历史上的《金瓶梅》、《红楼梦》，等等……，反映的都是社会真实。正如米兰•昆德拉在小说中说的：“暴露了一个建立在轮回不存在之上的世界所固有的深刻的道德沉沦，因为在这个世界上，一切都预先被晾解了，一切也就被卑鄙地许可了。”这个世界已经道德沉沦，是一个丧失了人的道德和任何责任、义务的“生命之轻”的世界。美，只存在于“被背弃的世界”。发人深省！
总之，米兰•昆德拉的小说对人生问题、哲理范畴涉及之广泛，思辩之丰富，是很值得人们去思考和探索的。

如果，你的英文基础很好，可以尝试看···
不过，翻译版的，看起来很难懂
要看几遍
才可以感觉出所表达的意思
托马斯的生活不是所有人都能理解的，你要好好的读！
希望我的回答你会满意

The Unbearable Lightness of Being (Czech: Nesnesitelná lehkost bytí) is a 1984 novel by Milan Kundera, about two women, two men, a dog and their lives in thePrague Spring period of Czechoslovak history in 1968. Although written in 1982, this novel was not published until two years later, in a French translation (asL'Insoutenable légèreté de l'être). The original Czech text was published the following year.
Premise[edit]
The Unbearable Lightness of Being takes place mainly in Prague in the late 1960s and 1970s. It explores the artistic and intellectual life of Czech society from the Prague Spring of 1968 to the invasion of Czechoslovakia by the Soviet Union and three other Warsaw Pact countries and its aftermath. The main characters are: Tomáš, a surgeon; his wife Tereza, a photographer anguished by her husband's infidelities; Tomáš’s lover Sabina, a free-spirited artist; Franz, a Swiss university professor and lover of Sabina; and finally Šimon, Tomáš’s estranged son from an earlier marriage.
Characters[edit]
Tomáš: A Czech surgeon and intellectual. Tomáš is a womanizer who lives for his work. He considers sex and love to be distinct entities: he has sex with many women but loves only his wife, Tereza. He sees no contradiction between these two positions. He explains womanizing as an imperative to explore female idiosyncrasies only expressed during sex. At first he views his wife as a burden whom he is obliged to take care of. After the Russian invasion, they escape toGeneva, where he starts womanizing again. Tereza, homesick, returns to Prague with the dog. He quickly realizes he wants to be with her and follows her home. He has to deal with the consequences of a letter to the editor in which he metaphorically likened the Czech Communists to Oedipus. Eventually fed up with life in Prague under the Communist regime, he moves to the countryside with Tereza. He abandons his twin obsessions of work and womanizing and discovers true happiness with Tereza. His epitaph, written by his Catholic son, is "He Wanted the Kingdom of God on Earth".
Tereza: Young wife of Tomáš. A gentle, intellectual photographer, she delves into dangerous and dissident photojournalism during the Soviet occupation of Prague. Tereza does not condemn Tomáš for his infidelities, instead characterizing herself as a weaker person. Tereza is mostly defined by her view of the body as disgusting and shameful, due to her mother's embrace of the body's grotesque functions. Throughout the book she fears simply being another body in Tomáš' array of women. Once Tomáš and Tereza move to the countryside, she devotes herself to raising cattle and reading. During this time she learns about her anima through an adoration of pet animals, reaching the conclusion that they were the last link to the paradise abandoned by Adam and Eve and becomes alienated from other people.
Sabina: Tomáš' mistress and closest friend. Sabina lives her life as an extreme example of lightness, taking profound satisfaction in the act of betrayal. She declares war on kitsch and struggles against the constraints imposed by her puritan ancestry and the Communist Party. This struggle is shown through her paintings. She occasionally expresses excitement at humiliation, shown through the use of her grandfather's bowler hat, a symbol that is born during one sexual encounter with Tomáš, before it eventually changes meaning and becomes a relic of the past. Later in the novel she begins to correspond with Šimon while living under the roof of some older Americans who admire her artistic skill.
Franz: Sabina's lover and a Geneva professor and idealist. Franz falls in love with Sabina, whom he considers a liberal and romantically tragic Czech dissident. He is a kind and compassionate man. As one of the novel's dreamers, he bases his actions on loyalty to the memories of his mother and of Sabina. His life revolves completely around books and academia, eventually to the extent that he seeks lightness and ecstasy by participating in marches and protests, the last of which is a march in Thailand to the border with Cambodia. In Bangkok after the march, he is mortally wounded during a mugging.
Karenin: The dog of Tomáš and Tereza. Although she is a bitch, the name is a masculine one and is a reference to Alexei Karenin, the husband in Anna Karenina. Karenin displays extreme dislike of change. Once moved to the countryside, Karenin becomes more content as she is able to enjoy more attention from her owners. She also quickly befriends a pig named Mefisto. During this time Tomáš discovers that Karenin has cancer and even after removing a tumor it is clear that Karenin is going to die. On her deathbed she unites Tereza and Tomáš through her "smile" at their attempts to improve her health.
Challenging Friedrich Nietzsche's concept of eternal recurrence (the idea that the universe and its events have already occurred and will recur ad infinitum), the story's thematic meditations posit the alternative: that each person has only one life to live and that which occurs in life occurs only once and never again — thus the "lightness" of being. In contrast, the concept of eternal recurrence imposes a "heaviness" on life and the decisions that are made--to borrow from Nietzsche's metaphor, it gives them "weight". Nietzsche believed this heaviness could be either a tremendous burden or great benefit depending on the individual's perspective.
The "unbearable lightness" in the title also refers to the lightness of love and sex, which are themes of the novel. Kundera portrays love as fleeting, haphazard and perhaps based on endless strings of coincidences, despite holding much significance for humans.
In the novel, Nietzsche's concept is attached to an interpretation of the German adage Einmal ist keinmal ("one occurrence is not significant"), namely an "all-or-nothing" cognitive distortion that Tomáš must overcome in his hero's journey. He initially believes "If we only have one life to live, we might as well not have lived at all," and specifically (with respect to committing to Tereza) "There is no means of testing which decision is better, because there is no basis for comparison." The novel resolves this question decisively that such a commitment is in fact possible and desirable.

个人认为这本书的现实意义远远超越了昆德拉所叙述的爱情……
这本书是属于所有的·而不是一部分的·
我读这本书用了大概两年时间吧。但还是认为没有把它读透……
《不能承受的生命之轻》大约是一本值得也很需要用很长的时间来阅读的吧……