"You have been (вы были), I fancy (/как/ я представляю), in essence a disappointed man all your life (по сути, разочарованным человеком всю вашу жизнь). You have been the rolling stone (вы были перекати-поле: «катящимся камнем») — and you have gathered very little moss (и вы собрали очень мало мха = не обросли деньгами/состоянием). You were particularly jealous of your brother's wealth (вы особенно завидовали богатству вашего брата)."

vigorous ['vrs], essence ['esns], wealth [wel]

"Your brother was an extremely healthy and vigorous man. There might be children and your chance of inheriting your brother's wealth would vanish."

"You have been, I fancy, in essence a disappointed man all your life. You have been the rolling stone — and you have gathered very little moss. You were particularly jealous of your brother's wealth."

"I repeat then (я повторяю затем) that, turning over various schemes in your mind (что /в тот момент, когда вы/ проворачивали различные схемы в вашем уме), your meeting with Mr. Cust gave you an idea (ваша встреча с мистером Кастом натолкнула вас на мысль: «дала вам идею»). His bombastic Christian names (его помпезные имена), his account of his epileptic seizures (его рассказ об эпилептических припадках) and of his headaches (и его головных болях), his whole shrinking and insignificant personality (его вся пугливая и незначительная личность; to shrink — уменьшаться, сокращаться; сжиматься, съеживаться; отскочить; отпрянуть, отшатнуться), struck you (поразила вас) as fitting him for the tool you wanted (как подгонка = возможностью подогнать его под инструмент, в котором вы нуждались). The whole alphabetical plan sprang into your mind (целая алфавитная схема появилась в вашем уме) — Cust's initials (инициалы Каста) — the fact (тот факт) that your brother's name began with a C (что имя вашего брата начиналось с /буквы/ «си») and that he lived at Churston (и что он жил в Черстоне) were the nucleus of the scheme (были ядром схемы). You even went so far (вы даже пошли так далеко) as to hint to Cust at his possible end (что намекнули Касту на его возможный конец) — though you could hardly hope (хотя вы едва ли могли надеяться) that that suggestion would bear the rich fruit that it did (что это предположение принесет /столь/ богатые плоды, как оно сделало)."

seizure ['si:], nucleus ['nju:kls], fruit [fru:t]

"I repeat then that, turning over various schemes in your mind, your meeting with Mr. Cust gave you an idea. His bombastic Christian names, his account of his epileptic seizures and of his headaches, his whole shrinking and insignificant personality, struck you as fitting him for the tool you wanted. The whole alphabetical plan sprang into your mind — Cust's initials — the fact that your brother's name began with a C and that he lived at Churston were the nucleus of the scheme. You even went so far as to hint to Cust at his possible end — though you could hardly hope that that suggestion would bear the rich fruit that it did."