1890-1938 1893-1974 20thcentury contributionsinphilosophicalanthropologyplessner correspondence correspondencekönig correspondenceplessner correspondencetrubet͡skoĭ eurasianschool germany helmuth history josef neo-kantianism nikolaĭsergeevich petrpetrovich philosophers philosophicalanthropology slaviclanguages suvchinskiĭ transcendentalism николайсергеевич петрпетрович сувчинский трубецкой